ZnO nanowires(ZnO NWs),ZnO nanoparticles(ZnO NPs)and carbon dots(C-dots)were synthesized by hydrothermal,sol-gel and hydrothermal methods respectively.They were also characterized and applied for dye sensitized solar ...ZnO nanowires(ZnO NWs),ZnO nanoparticles(ZnO NPs)and carbon dots(C-dots)were synthesized by hydrothermal,sol-gel and hydrothermal methods respectively.They were also characterized and applied for dye sensitized solar cells(DSSCs).The effects of C-dots on ZnO NWs and ZnO NPs have been evaluated.The C-dots were used at a mole ratio of citric acid(CA)to ethylene diamine(EDA)of 1:1.5.These C-dots were found to enhance the performance of the flexible electrode DSSCs.After the addition of C-dots,the power conversion efficiency(PCE)of ZnO NPs was boosted to be two times higher than that of ZnO NPs DSSCs without C-dots.Similarly,the ultraviolet(UV)-band revealed a blue shift,resulting in a lower band gap and a reduced charge transfer resistance,which can enhance the PCE of DSSCs.The loaded quantity on the flexible electrode substrate made of polyethylene terephthalate(PET)was optimized(50 mg).For DSSCs,the PET flexible electrode conductive polymer has produced positive outcomes.For ZnO NWs and ZnO NWs@C-dots,the PCE values were 1.45%and 4.25%;while for ZnO NPs and ZnO NPs@C-dots,they were 2.34%and 5.81%,respectively.This work achieved remarkable and competitive performance when compared to solid(indium tin oxides/glass)-based substrate.展开更多
Flexible polymer-based dye-sensitized solar cells (DSSCs) offer promising potential for lightweight, cost-effective and versatile photovoltaic applications. However, the critical challenge in their widespread applicat...Flexible polymer-based dye-sensitized solar cells (DSSCs) offer promising potential for lightweight, cost-effective and versatile photovoltaic applications. However, the critical challenge in their widespread applications is the weak thermal stability of most polymeric substrates, which can only withstand a maximum temperature processing of 150˚C. In this study, a facile and low-cost strategy is proposed to develop at low temperature DSSC flexible photoanode based on a polymeric matrix. Highly porous nanocomposites fibrous mats composed of polyethylene terephthalate (PET) and titanium dioxide (TiO2) nanobars were prepared through an electrospinning process using different configurations (uniaxial electrospinning, coaxial electrospinning, and electrospray-assisted electrospinning). These techniques enabled precise control of the microstructure and the positioning of TiO2 within the composite nanofibers. Therefore, the as-produced photoanodes were loaded with N719 dye and tested in DSSC prototype using iodide-triiodide electrolyte and platinum (Pt) coated counter electrode. The results show that incorporating TiO2 on the fiber surface through the electrospray-assisted electrospinning enhanced the performance of the nanofiber composite, leading to improved dye loading capacity, electron transfer efficiency and photovoltaic performance.展开更多
Herein, we report the design and synthesis of three new D-A type metal-free carbazole based dyes（S1-3）as effective co-sensitizers for dye-sensitized solar cell（DSSC） sensitized with Ru（Ⅱ） complex（NCSU-10）.In ...Herein, we report the design and synthesis of three new D-A type metal-free carbazole based dyes（S1-3）as effective co-sensitizers for dye-sensitized solar cell（DSSC） sensitized with Ru（Ⅱ） complex（NCSU-10）.In this new design, the electron rich carbazole unit was attached to three different electron withdrawing/anchoring species, viz. 4-amino benzoic acid, sulfanilic acid and barbituric acid. The dyes were characterized by spectral, photophysical and electrochemical analysis. Their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of the structures of these co-sensitizers on the photovoltaic performances. Further, S1-3 dyes were co-sensitized along with a well-known NCSU-10 dye in order to broaden the spectral response of the co-sensitized devices and hence improve the efficiency. The photovoltaic performance studies indicated that, the device fabricated using S1 dye as co-sensitizer with 0.2 mM of NCSU-10 exhibited improved PCE of 9.55% with JSC of 22.85 mA cm-2, VOC of 0.672 V and FF of 62.2%, whereas the DSSC fabricated with dye NCSU-10（0.2 mM） alone displayed PCE of 8.25% with JSC of 20.41 mA cm-2, VOC of 0.667 V and FF of 60.6%. Furthermore, electronic excitations simulated using time-dependent DFT, were in good agreement with the experimentally obtained results of the co-sensitizers, indicating that the exchange-correlation function and basis set utilized for predicting the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs.展开更多
The paper reports the fabrication of Zn-doped TiO_2 nanotubes(Zn-TONT)/ZnO nanoflakes heterostructure for the first time,which shows improved performance as a photoanode in dye-sensitized solar cell(DSSC).The layered ...The paper reports the fabrication of Zn-doped TiO_2 nanotubes(Zn-TONT)/ZnO nanoflakes heterostructure for the first time,which shows improved performance as a photoanode in dye-sensitized solar cell(DSSC).The layered structure of this novel nanoporous structure has been analyzed unambiguously by Rutherford backscattering spectroscopy,scanning electron microscopy,and X-ray diffractometer.The cell using the heterostructure as photoanode manifests an enhancement of about an order in the magnitude of the short circuit current and a seven-fold increase in efficiency,over pure TiO_2 photoanodes.Characterizations further reveal that the Zn-TONT is preferentially oriented in [001] direction and there is a Ti metal-depleted interface layer which leads to better band alignment in DSSC.展开更多
Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require comple...Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require complex preparation process. Herein, waste lignin, recycled from hazardous black liquors,is used to create oxygen-nitrogen-sulfur codoped carbon microspheres for use in DSSC CEs through the facile process of low-temperature preoxidation and high-temperature self-activation. The large number of ester bonds formed by preoxidation increase the degree of cross-linking of the lignin chains, leading to the formation of highly disordered carbon with ample defect sites during pyrolysis. The presence of organic O/N/S components in the waste lignin results in high O/N/S doping of the pyrolysed carbon,which increases the electrolyte ion adsorption and accelerates the electron transfer at the CE/electrolyte interface, as confirmed by density functional theory(DFT) calculations. The presence of inorganic impurities enables the construction of a hierarchical micropore-rich carbon structure through the etching effect during self-activation, which can provide abundant catalytically active sites for the reversible adsorption/desorption of electrolyte ions. Under these synergistic effects, the DSSCs that use this novel carbon CE achieve a quite high power-conversion efficiency of 9.22%. To the best of our knowledge, the value is a new record reported so far for biomass-carbon-based DSSCs.展开更多
文摘ZnO nanowires(ZnO NWs),ZnO nanoparticles(ZnO NPs)and carbon dots(C-dots)were synthesized by hydrothermal,sol-gel and hydrothermal methods respectively.They were also characterized and applied for dye sensitized solar cells(DSSCs).The effects of C-dots on ZnO NWs and ZnO NPs have been evaluated.The C-dots were used at a mole ratio of citric acid(CA)to ethylene diamine(EDA)of 1:1.5.These C-dots were found to enhance the performance of the flexible electrode DSSCs.After the addition of C-dots,the power conversion efficiency(PCE)of ZnO NPs was boosted to be two times higher than that of ZnO NPs DSSCs without C-dots.Similarly,the ultraviolet(UV)-band revealed a blue shift,resulting in a lower band gap and a reduced charge transfer resistance,which can enhance the PCE of DSSCs.The loaded quantity on the flexible electrode substrate made of polyethylene terephthalate(PET)was optimized(50 mg).For DSSCs,the PET flexible electrode conductive polymer has produced positive outcomes.For ZnO NWs and ZnO NWs@C-dots,the PCE values were 1.45%and 4.25%;while for ZnO NPs and ZnO NPs@C-dots,they were 2.34%and 5.81%,respectively.This work achieved remarkable and competitive performance when compared to solid(indium tin oxides/glass)-based substrate.
文摘Flexible polymer-based dye-sensitized solar cells (DSSCs) offer promising potential for lightweight, cost-effective and versatile photovoltaic applications. However, the critical challenge in their widespread applications is the weak thermal stability of most polymeric substrates, which can only withstand a maximum temperature processing of 150˚C. In this study, a facile and low-cost strategy is proposed to develop at low temperature DSSC flexible photoanode based on a polymeric matrix. Highly porous nanocomposites fibrous mats composed of polyethylene terephthalate (PET) and titanium dioxide (TiO2) nanobars were prepared through an electrospinning process using different configurations (uniaxial electrospinning, coaxial electrospinning, and electrospray-assisted electrospinning). These techniques enabled precise control of the microstructure and the positioning of TiO2 within the composite nanofibers. Therefore, the as-produced photoanodes were loaded with N719 dye and tested in DSSC prototype using iodide-triiodide electrolyte and platinum (Pt) coated counter electrode. The results show that incorporating TiO2 on the fiber surface through the electrospray-assisted electrospinning enhanced the performance of the nanofiber composite, leading to improved dye loading capacity, electron transfer efficiency and photovoltaic performance.
基金Department of Textile Engineering, Chemistry and Science at North Carolina State University for the financial support
文摘Herein, we report the design and synthesis of three new D-A type metal-free carbazole based dyes（S1-3）as effective co-sensitizers for dye-sensitized solar cell（DSSC） sensitized with Ru（Ⅱ） complex（NCSU-10）.In this new design, the electron rich carbazole unit was attached to three different electron withdrawing/anchoring species, viz. 4-amino benzoic acid, sulfanilic acid and barbituric acid. The dyes were characterized by spectral, photophysical and electrochemical analysis. Their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of the structures of these co-sensitizers on the photovoltaic performances. Further, S1-3 dyes were co-sensitized along with a well-known NCSU-10 dye in order to broaden the spectral response of the co-sensitized devices and hence improve the efficiency. The photovoltaic performance studies indicated that, the device fabricated using S1 dye as co-sensitizer with 0.2 mM of NCSU-10 exhibited improved PCE of 9.55% with JSC of 22.85 mA cm-2, VOC of 0.672 V and FF of 62.2%, whereas the DSSC fabricated with dye NCSU-10（0.2 mM） alone displayed PCE of 8.25% with JSC of 20.41 mA cm-2, VOC of 0.667 V and FF of 60.6%. Furthermore, electronic excitations simulated using time-dependent DFT, were in good agreement with the experimentally obtained results of the co-sensitizers, indicating that the exchange-correlation function and basis set utilized for predicting the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs.
基金UGC-DAE CSR,Indore,for funding through a collaborative project and SAIF IIT Bombay for the help with SEMsupported by the Michigan Space Grant Consortium+1 种基金by Hope CollegeDAE-BRNS for funding the preliminary works
文摘The paper reports the fabrication of Zn-doped TiO_2 nanotubes(Zn-TONT)/ZnO nanoflakes heterostructure for the first time,which shows improved performance as a photoanode in dye-sensitized solar cell(DSSC).The layered structure of this novel nanoporous structure has been analyzed unambiguously by Rutherford backscattering spectroscopy,scanning electron microscopy,and X-ray diffractometer.The cell using the heterostructure as photoanode manifests an enhancement of about an order in the magnitude of the short circuit current and a seven-fold increase in efficiency,over pure TiO_2 photoanodes.Characterizations further reveal that the Zn-TONT is preferentially oriented in [001] direction and there is a Ti metal-depleted interface layer which leads to better band alignment in DSSC.
基金supported by the National Natural Science Foundation of China (31890771 and 31901249)the Young Elite Scientists Sponsorship Program by CAST (2019QNRC001)+3 种基金the Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology (2020RC3041)the Training Program for Excellent Young Innovators of Changsha (kq2106056)the Hunan Provincial Natural Science Foundation of China (2022JJ30079)the Postgraduate Technology Innovation Project of Central South University of Forestry and Technology (2022CX02017)。
文摘Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require complex preparation process. Herein, waste lignin, recycled from hazardous black liquors,is used to create oxygen-nitrogen-sulfur codoped carbon microspheres for use in DSSC CEs through the facile process of low-temperature preoxidation and high-temperature self-activation. The large number of ester bonds formed by preoxidation increase the degree of cross-linking of the lignin chains, leading to the formation of highly disordered carbon with ample defect sites during pyrolysis. The presence of organic O/N/S components in the waste lignin results in high O/N/S doping of the pyrolysed carbon,which increases the electrolyte ion adsorption and accelerates the electron transfer at the CE/electrolyte interface, as confirmed by density functional theory(DFT) calculations. The presence of inorganic impurities enables the construction of a hierarchical micropore-rich carbon structure through the etching effect during self-activation, which can provide abundant catalytically active sites for the reversible adsorption/desorption of electrolyte ions. Under these synergistic effects, the DSSCs that use this novel carbon CE achieve a quite high power-conversion efficiency of 9.22%. To the best of our knowledge, the value is a new record reported so far for biomass-carbon-based DSSCs.
