Photoinduced intermolecular charge transfer(PICT)determines the voltage loss in bulk heterojunction(BHJ)organic photovoltaics(OPVs),and this voltage loss can be minimized by inducing efficient PICT,which requires ener...Photoinduced intermolecular charge transfer(PICT)determines the voltage loss in bulk heterojunction(BHJ)organic photovoltaics(OPVs),and this voltage loss can be minimized by inducing efficient PICT,which requires energy-state matching between the donor and acceptor at the BHJ interfaces.Thus,both geometrically and energetically accessible delocalized state matching at the hot energy level is crucial for achieving efficient PICT.In this study,an effective method for quantifying the hot state matching of OPVs was developed.The degree of energy-state matching between the electron donor and acceptor at BHJ interfaces was quantified using a mismatching factor(MF)calculated from the modified optical density of the BHJ.Furthermore,the correlation between the open-circuit voltage(Voc)of the OPV device and energy-state matching at the BHJ interface was investigated using the calculated MF.The OPVs with small absolute MF values exhibited high Voc values.This result clearly indicates that the energy-state matching between the donor and acceptor is crucial for achieving a high Voc in OPVs.Because the MF indicates the degree of energy-state matching,which is a critical factor for suppressing energy loss,it can be used to estimate the Voc loss in OPVs.展开更多
The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little att...The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.展开更多
The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 (CZTSe) thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface s...The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 (CZTSe) thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface sulfurization of CZTSe thin films is carried out by using one technique that does not utilize toxic H2S gas; a sequential evaporation of SnS after CZTSe deposition and the annealing of CZTSe thin films in selenium vapor. A Cu2ZnSn(S, Se)4 (CZTSSe) thin layer is grown on the surface of the CZTSe thin film after the annealing. The conversion efficiency of the completed device is improved due to the enhancement of Voc, which could be attributed to the formation of a hole-recombination barrier at the surface or the passivation of the surface and grain boundary by S incorporation.展开更多
The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logar...The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).展开更多
This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-Si...This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-SiC:H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely. A significant improvement in open circuit voltage has been obtained by using high quality p-~SiC:H films optimized at the "low-power regime" under low silane flow rates and high hydrogen dilution conditions.展开更多
It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric ac...It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (</span><i><span style="font-size:12px;font-family:Verdana;">J</span><sub><span style="font-size:12px;font-family:Verdana;">sc</span></sub></i><span style="font-size:12px;font-family:Verdana;">), fill factor (FF), open-circuit voltage (</span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;">) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">NH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">PbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;"> (MAPbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">) precursor solution was 1</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">wt%, the device obtained the smallest </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> decay (less than 1%) in the p-i-n type PSCs with poly</span></span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C</span><sub><span style="font-size:12px;font-family:Verdana;">60</span></sub><span style="font-size:12px;font-family:Verdana;">) as electron transport layer (ETL). The PSCs </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> stability improvement is attri</span><span style="font-size:12px;font-family:Verdana;">buted to enhanced crystallinity of photoactive layer and decreased non-radiative </span><span style="font-size:12px;font-family:Verdana;">recombination by PCBM doping in the perovskites.</span></span></span></span>展开更多
<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span&g...<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">within the base region of p-n junction polycrystalline solar </span><span style="font-family:Verdana;">cell</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">in transient mode.</span><span style="font-family:""> </span><span style="font-family:Verdana;">This work is an experimental transient</span><span style="font-family:Verdana;"> 3-Dimensionnal study.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The magnitude of the magnetic field B is varied from 0 mT to 0.045 mT. Indeed, the solar cell is illuminated by a stroboscopic flash with air mass 1.5</span><span style="font-family:""> </span><span style="font-family:Verdana;">and under magnetic field in transient state.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The experimental details are assumed in a figure. The procedure is outlined by the Open Circuit Voltage Decay analysis. Effective minority carrier life-time is calculated by fitting the linear zone of the transient voltage decay curve</span><span style="font-family:""> </span><span style="font-family:Verdana;">because linear decay is an ideal decay. The kaleidagraph software permits access to the slope of the curve which is inversely proportional to the</span><span style="font-family:""> </span><span style="font-family:Verdana;">lifetime. The external magnetic effects</span><span style="font-family:""> </span><span style="font-family:Verdana;">on minority carriers’ effective lifetime </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> then</span><span style="font-family:""> </span><span style="font-family:Verdana;">presented and analyzed.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The analysis show</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> that the charge carrier</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s effective lifetime decrease with the magnetic field increase.</span>展开更多
The possibility of the increase in open-circuit voltage of organic photovoltaic cells based primarily indium-tin oxide (ITO)/rubrene/fullerene/Al structure by changing the work function of ITO anodes and Al cathodes w...The possibility of the increase in open-circuit voltage of organic photovoltaic cells based primarily indium-tin oxide (ITO)/rubrene/fullerene/Al structure by changing the work function of ITO anodes and Al cathodes was described in this work. To change built-in potential preferably in order to increase the open-circuit voltage, the work function of ITO should be increased and work function of Al should be decreased. The correlation between the change in work functions of electrodes and performance of the organic photovoltaic cells before and after surface modifications was examined in detail. The enhancement of open-circuit voltage depends on a function of work function change of both ITO and Al electrode. We could show that the built-in potential in the cells played an important role in open-circuit voltage.展开更多
It is shown that the nonideality coefficient m actually depends on the electron temperature Te, and the hole temperature Th. We get more general expression for the nonideality coefficient, taking into account the conc...It is shown that the nonideality coefficient m actually depends on the electron temperature Te, and the hole temperature Th. We get more general expression for the nonideality coefficient, taking into account the concentration of electrons and holes, as well as their temperature, coefficient and diffusion length, the temperature of the phonons, the applied voltage, and the height of the potential barrier.展开更多
CdSe quantum dot sensitized solar cells (QDSCs) modified with graphene quantum dots (GQDs) have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage (Voc) of the...CdSe quantum dot sensitized solar cells (QDSCs) modified with graphene quantum dots (GQDs) have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage (Voc) of the modified QDSCs was approximately 0.04 V higher than that of plain CdSe QDSCs, consequently improving the photovoltaic performance of the resulting QDSCs. Served as a novel coating on the CdSe QD sensitized photoanode, GQDs played a vital role in improving Voc due to the suppressed charge recombination which has been confirmed by electron impedance spectroscopy as well as transient photovoltage decay measure- ments. Moreover, different adsorption sequences, concentration and deposition time of GQDs have also been systematically investigated to boost the power conversion efficiency (PCE) of CdSe QDSCs. After the coating of CdSe with GQDs, the resulting champion CdSe QDSCs exhibited an improved PCE of 6.59% under AM 1.5G full one sun illumination.展开更多
The monocrystalline silicon is a promising material that could be used in solar cells that convert light into electricity. Although the cost of ordinary silicon (Si) solar cells has decreased significantly over the pa...The monocrystalline silicon is a promising material that could be used in solar cells that convert light into electricity. Although the cost of ordinary silicon (Si) solar cells has decreased significantly over the past two decades, the conversion efficiency of these cells has remained relatively high. While solar cells have a great potential as a device of renewable energy, the high cost they incur per Watt continues to be a significant barrier to their widespread implementation. As a consequence, it is vital to conduct research into alternate materials that may be used in the construction of solar cells. The heterojunction solar cell (HJSC), which is based on n-type zinc oxide (n-ZnO) and p-type silicon (p-Si), is one of the numerous alternatives of the typical Si single homojunction solar cell. There are many deficiencies that can be found in the published research on n-ZnO/p-Si heterojunction solar cell. Inconsistencies in the stated value of open circuit voltage (V<sub>oc</sub>) of the solar cell are one example of deficiency. The absence of a full theoretical study to evaluate the potential of the solar cell structure is another deficiency that can be found in these researches. A lower value of experimentally obtained V<sub>OC</sub> in comparison to the theoretical prediction based on the band-gap between n-ZnO and p-Si. There needs to be more consensus among scientists regarding the optimal conditions for the growth of zinc oxide. Many software’s are available for simulating and optimizing the solar cells based on these parameters. For this purpose, in this dissertation, I provide computational results relevant to n-ZnO/p-Si HJSC to overcome deficiencies that have been identified. While modeling and simulating the potential of the solar cell structure with AFORS-HET, it is essential to consider the constraints that exist in the real world. AFORS-HET was explicitly designed to mimic the multilayer solar cell arrangement. In AFORS-HET, we can add up to seven layers for solar cell layout. By using this software, we can figure out the open circuit voltage (V<sub>OC</sub>), the short circuit current (J<sub>SC</sub>), the quantum efficiency (QE, %), the heterojunction energy band structure, and the power conversion efficiency (PCE).展开更多
基金National Research Foundation of Korea,Grant/Award Number:2022R1A6A1A03051158BrainLink Program,Grant/Award Number:2022H1D3A3A01077343Nano Material Technology Development Program,Grant/Award Number:2021M3H4A1A02057007。
文摘Photoinduced intermolecular charge transfer(PICT)determines the voltage loss in bulk heterojunction(BHJ)organic photovoltaics(OPVs),and this voltage loss can be minimized by inducing efficient PICT,which requires energy-state matching between the donor and acceptor at the BHJ interfaces.Thus,both geometrically and energetically accessible delocalized state matching at the hot energy level is crucial for achieving efficient PICT.In this study,an effective method for quantifying the hot state matching of OPVs was developed.The degree of energy-state matching between the electron donor and acceptor at BHJ interfaces was quantified using a mismatching factor(MF)calculated from the modified optical density of the BHJ.Furthermore,the correlation between the open-circuit voltage(Voc)of the OPV device and energy-state matching at the BHJ interface was investigated using the calculated MF.The OPVs with small absolute MF values exhibited high Voc values.This result clearly indicates that the energy-state matching between the donor and acceptor is crucial for achieving a high Voc in OPVs.Because the MF indicates the degree of energy-state matching,which is a critical factor for suppressing energy loss,it can be used to estimate the Voc loss in OPVs.
基金Supported by National Natural Science Foundation of China(Grant No.51507012)Beijing Municipal Natural Science Foundation of China(Grant No.3182035)
文摘The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20120031110039
文摘The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 (CZTSe) thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface sulfurization of CZTSe thin films is carried out by using one technique that does not utilize toxic H2S gas; a sequential evaporation of SnS after CZTSe deposition and the annealing of CZTSe thin films in selenium vapor. A Cu2ZnSn(S, Se)4 (CZTSSe) thin layer is grown on the surface of the CZTSe thin film after the annealing. The conversion efficiency of the completed device is improved due to the enhancement of Voc, which could be attributed to the formation of a hole-recombination barrier at the surface or the passivation of the surface and grain boundary by S incorporation.
基金Project(11374094)supported by the National Natural Science Foundation of ChinaProject(2013HZX23)supported by Natural Science Foundation of Hunan University of Technology,ChinaProject(2015JJ3060)supported by Natural Science Foundation of Hunan Province of China
文摘The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2009AA05Z422), the National Basic Research Program of China (Grant Nos. 2011CBA00705, 2011CBA00706, and 2011CBA00707), and the Natural Science Foundation of Tianjin (Grant No. 08JCZDJC22200).
文摘This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-SiC:H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely. A significant improvement in open circuit voltage has been obtained by using high quality p-~SiC:H films optimized at the "low-power regime" under low silane flow rates and high hydrogen dilution conditions.
文摘It is well known that [6,6]-phenyl-C<sub><span style="font-size:12px;font-family:Verdana;">61</span></sub><span style="font-size:12px;font-family:Verdana;">-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (</span><i><span style="font-size:12px;font-family:Verdana;">J</span><sub><span style="font-size:12px;font-family:Verdana;">sc</span></sub></i><span style="font-size:12px;font-family:Verdana;">), fill factor (FF), open-circuit voltage (</span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;">) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">NH</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">PbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;"> (MAPbI</span><sub><span style="font-size:12px;font-family:Verdana;">3</span></sub><span style="font-size:12px;font-family:Verdana;">) precursor solution was 1</span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">wt%, the device obtained the smallest </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> decay (less than 1%) in the p-i-n type PSCs with poly</span></span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "=""><span style="font-size:12px;font-family:Verdana;">(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C</span><sub><span style="font-size:12px;font-family:Verdana;">60</span></sub><span style="font-size:12px;font-family:Verdana;">) as electron transport layer (ETL). The PSCs </span><i><span style="font-size:12px;font-family:Verdana;">V</span><sub><span style="font-size:12px;font-family:Verdana;">oc</span></sub></i><span style="font-size:12px;font-family:Verdana;"> stability improvement is attri</span><span style="font-size:12px;font-family:Verdana;">buted to enhanced crystallinity of photoactive layer and decreased non-radiative </span><span style="font-size:12px;font-family:Verdana;">recombination by PCBM doping in the perovskites.</span></span></span></span>
文摘<span style="font-family:Verdana;">This manuscript presents a simple method for excess minority carriers’ lifetime measurement</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">within the base region of p-n junction polycrystalline solar </span><span style="font-family:Verdana;">cell</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">in transient mode.</span><span style="font-family:""> </span><span style="font-family:Verdana;">This work is an experimental transient</span><span style="font-family:Verdana;"> 3-Dimensionnal study.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The magnitude of the magnetic field B is varied from 0 mT to 0.045 mT. Indeed, the solar cell is illuminated by a stroboscopic flash with air mass 1.5</span><span style="font-family:""> </span><span style="font-family:Verdana;">and under magnetic field in transient state.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The experimental details are assumed in a figure. The procedure is outlined by the Open Circuit Voltage Decay analysis. Effective minority carrier life-time is calculated by fitting the linear zone of the transient voltage decay curve</span><span style="font-family:""> </span><span style="font-family:Verdana;">because linear decay is an ideal decay. The kaleidagraph software permits access to the slope of the curve which is inversely proportional to the</span><span style="font-family:""> </span><span style="font-family:Verdana;">lifetime. The external magnetic effects</span><span style="font-family:""> </span><span style="font-family:Verdana;">on minority carriers’ effective lifetime </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> then</span><span style="font-family:""> </span><span style="font-family:Verdana;">presented and analyzed.</span><span style="font-family:""> </span><span style="font-family:Verdana;">The analysis show</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> that the charge carrier</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s effective lifetime decrease with the magnetic field increase.</span>
文摘The possibility of the increase in open-circuit voltage of organic photovoltaic cells based primarily indium-tin oxide (ITO)/rubrene/fullerene/Al structure by changing the work function of ITO anodes and Al cathodes was described in this work. To change built-in potential preferably in order to increase the open-circuit voltage, the work function of ITO should be increased and work function of Al should be decreased. The correlation between the change in work functions of electrodes and performance of the organic photovoltaic cells before and after surface modifications was examined in detail. The enhancement of open-circuit voltage depends on a function of work function change of both ITO and Al electrode. We could show that the built-in potential in the cells played an important role in open-circuit voltage.
文摘It is shown that the nonideality coefficient m actually depends on the electron temperature Te, and the hole temperature Th. We get more general expression for the nonideality coefficient, taking into account the concentration of electrons and holes, as well as their temperature, coefficient and diffusion length, the temperature of the phonons, the applied voltage, and the height of the potential barrier.
基金supported by the National Natural Science Foundation of China (21175043,91233102)the Fundamental Research Funds for the Central Universities for financial support
文摘CdSe quantum dot sensitized solar cells (QDSCs) modified with graphene quantum dots (GQDs) have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage (Voc) of the modified QDSCs was approximately 0.04 V higher than that of plain CdSe QDSCs, consequently improving the photovoltaic performance of the resulting QDSCs. Served as a novel coating on the CdSe QD sensitized photoanode, GQDs played a vital role in improving Voc due to the suppressed charge recombination which has been confirmed by electron impedance spectroscopy as well as transient photovoltage decay measure- ments. Moreover, different adsorption sequences, concentration and deposition time of GQDs have also been systematically investigated to boost the power conversion efficiency (PCE) of CdSe QDSCs. After the coating of CdSe with GQDs, the resulting champion CdSe QDSCs exhibited an improved PCE of 6.59% under AM 1.5G full one sun illumination.
文摘The monocrystalline silicon is a promising material that could be used in solar cells that convert light into electricity. Although the cost of ordinary silicon (Si) solar cells has decreased significantly over the past two decades, the conversion efficiency of these cells has remained relatively high. While solar cells have a great potential as a device of renewable energy, the high cost they incur per Watt continues to be a significant barrier to their widespread implementation. As a consequence, it is vital to conduct research into alternate materials that may be used in the construction of solar cells. The heterojunction solar cell (HJSC), which is based on n-type zinc oxide (n-ZnO) and p-type silicon (p-Si), is one of the numerous alternatives of the typical Si single homojunction solar cell. There are many deficiencies that can be found in the published research on n-ZnO/p-Si heterojunction solar cell. Inconsistencies in the stated value of open circuit voltage (V<sub>oc</sub>) of the solar cell are one example of deficiency. The absence of a full theoretical study to evaluate the potential of the solar cell structure is another deficiency that can be found in these researches. A lower value of experimentally obtained V<sub>OC</sub> in comparison to the theoretical prediction based on the band-gap between n-ZnO and p-Si. There needs to be more consensus among scientists regarding the optimal conditions for the growth of zinc oxide. Many software’s are available for simulating and optimizing the solar cells based on these parameters. For this purpose, in this dissertation, I provide computational results relevant to n-ZnO/p-Si HJSC to overcome deficiencies that have been identified. While modeling and simulating the potential of the solar cell structure with AFORS-HET, it is essential to consider the constraints that exist in the real world. AFORS-HET was explicitly designed to mimic the multilayer solar cell arrangement. In AFORS-HET, we can add up to seven layers for solar cell layout. By using this software, we can figure out the open circuit voltage (V<sub>OC</sub>), the short circuit current (J<sub>SC</sub>), the quantum efficiency (QE, %), the heterojunction energy band structure, and the power conversion efficiency (PCE).