Numerical Study and Optimization of CZTS-Based Thin-Film Solar Cell Structure with Different Novel Buffer-Layer Materials Using SCAPS-1D Software

This study explored the performances of CZTS-based thin-film solar cell with three novel buffer layer materials ZnS, CdS, and CdZnS, as well as with variation in thickness of buffer and absorber-layer, doping concentrations of absorber-layer material and operating temperature. Our aims focused to identify the most optimal thin-film solar cell structure that offers high efficiency and lower toxicity which are desirable for sustainable and eco-friendly energy sources globally. SCAPS-1D, widely used software for modeling and simulating solar cells, has been used and solar cell fundamental performance parameters such as open-circuited voltage (), short-circuited current density (), fill-factor() and efficiency() have been optimized in this study. Based on our simulation results, it was found that CZTS solar cell with Cd0.4Zn0.6S as buffer-layer offers the most optimal combination of high efficiency and lower toxicity in comparison to other structure investigated in our study. Although the efficiency of Cd0.4Zn0.6S, ZnS and CdS are comparable, Cd0.4Zn0.6S is preferable to use as buffer-layer for its non-toxic property. In addition, evaluation of performance as a function of buffer-layer thickness for Cd0.4Zn0.6S, ZnS and CdS showed that optimum buffer-layer thickness for Cd0.4Zn0.6S was in the range from 50 to 150nm while ZnS offered only 50 – 75 nm. Furthermore, the temperature dependence performance parameters evaluation revealed that it is better to operate solar cell at temperature 290K for stable operation with optimum performances. This study would provide valuable insights into design and optimization of nanotechnology-based solar energy technology for minimizing global energy crisis and developing eco-friendly energy sources sustainable and simultaneously.

Simulation Study of CuO-Based Solar Cell with Different Buffer Layers Using SCAPS-1D

In copper oxide (CuO) based solar cells, various buffer layers such as CdS, In2S3, WS2 and IGZO have been investigated by solar cell capacitance simulator (SCAPS) in this work. By varying absorber and buffer layer thickness, photovoltaic parameters (open circuit voltage, fill factor, short-circuit current density and efficiency) are determined. The highest efficiency achieved is 19.6% with WS2 buffer layer. The impact of temperature on all CuO-based solar cells is also investigated.

Improved performance of polymer solar cells by using inorganic, organic, and doped cathode buffer layers

The interface between the active layer and the electrode is one of the most critical factors that could affect the device performance of polymer solar cells. In this work, based on the typical poly（3-hexylthiophene）：[6,6]-phenyl C61-butyric acid methyl ester （P3HT：PCBM） polymer solar cell, we studied the effect of the cathode buffer layer （CBL） between the top metal electrode and the active layer on the device performance. Several inorganic and organic materials commonly used as the electron injection layer in an organic light-emitting diode （OLED） were employed as the CBL in the P3HT：PCBM polymer solar cells. Our results demonstrate that the inorganic and organic materials like Cs2CO3, bathophenanthroline （Bphen）, and 8-hydroxyquinolatolithium （Liq） can be used as CBL to efficiently improve the device performance of the P3HT：PCBM polymer solar cells. The P3HT：PCBM devices employed various CBLs possess power conversion efficiencies （PCEs） of 3.0%-3.3%, which are ca. 50% improved compared to that of the device without CBL. Furthermore, by using the doped organic materials Bphen：Cs2CO3 and Bphen：Liq as the CBL, the PCE of the P3HT：PCBM device will be further improved to 3.5%, which is ca. 70% higher than that of the device without a CBL and ca. 10% increased compared with that of the devices with a neat inorganic or organic CBL.

Preparation and characterization of Cd_(1-x)Zn_xS buffer layers for thin film solar cells

Cd1_xZnxS （x = 0, 0.1, 0.2, 0.3, 1.0） thin films have been grown successfully on soda-lime glass substrates by chemical bath deposition technique as a very promising buffer layer material for optoelectronic device applications. The composition, structural properties, surface morphol- ogy, and optical properties of Cd~_xZnxS thin films were characterized by energy dispersive analysis of X-ray tech- nique （EDAX）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and UV-Vis spectrophotometer tech- niques, respectively. The annealed films were observed to possess the deficient sulfur composition. The results of XRD show that the Cdl_xZnxS （x = 0. l） thin film annealed at 450 ~C forms hexagonal （wurtzite） structure with lattice parameters a = 0.408814 nm, c ： 0.666059 nm, and its average grain size is 24.9902 nm. The diffraction peaks become strong with the increasing annealing temperatures. The surface of Cdl_~ZnxS （x = 0.1） thin film annealed at 450 ~C is uninterrupted and homogenous as compared to other temperatures. From optical properties, it is observed that the presence of small amount of Zn results in marked changes in the optical band gap of CdS. The band gaps of the Cdl_xZnxS thin films vary from 2.42 to 3.51 eV as composition varies from x = 0.0 to 1.0.

Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers

In this work, bathocuproine （BCP） and bathophenanthroline （Bphen）, commonly used in small-molecule organic solar cells （OSCs）, are adopted as the buffer layers to improve the performance of the polymer solar cells （PSCs） based on poly（2-methoxy-5-（2-ethylhexyloxy）-1,4-phenylenevinylene） （MEH-PPV）： [6,6]-phenyl-C61-butyric acid methyl ester （PCBM） bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-am BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen （i） increasing the optical field, and hence the absorption in the active layer, （ii） effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum （Al） interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance （Rs）, and （iii） preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.

High Performance for Cu(In,Ga)Se2 Quaternary System-Based Solar Cells with Alternative Buffer Layers

In this study, the authors investigated the performance of different buffer layers through the electrical parameters such as Jsc, Voc, QE and η of the quaternary system Cu(In,Ga)Se2 solar cells. The performance of Cu(In,Ga)Se2solar cells has been modeled and numerically simulated by using the SCAPS- 1D device simulation tool. The cells with a ZnSe, Zn(O,S) and (Zn,Mg)O buffer layers were compared with the reference CdS buffer layer. The investigation of ZnSe, Zn(O, S) and (Zn,Mg)O-based cells to substitute the traditional CdS in the future shows that the ZnSe-buffer layer is a potential material to replace CdS, which revealed the best efficiency of 20.76%, the other electrical parameters are: JSC = 34.6 mA/cm2, VOC = 0.76 V and FF = 79.6%. The losses as a function of the temperature are estimated at 0.1%/K, among all kinds of buffer layers studied. We have also shown that the use of a high band-gap buffer layer is necessary to obtain a better short-circuit current density JSC. From our results, we note that the chalcogenide solar cells with Zn-based alternative buffer layer have almost the same stability thatthe traditional CdS buffer layer solar cells have.

Improved performance of microcrystalline silicon solar cell with graded-band-gap silicon oxide buffer layer

Microcrystalline silicon（μc-Si：H） solar cell with graded band gap microcrystalline silicon oxide（μc-SiOx：H） buffer layer is prepared by plasma enhanced chemical vapor deposition and exhibits improved performance compared with the cell without it. The buffer layer moderates the band gap mismatch by reducing the barrier of the p/i interface, which promotes the nucleation of the i-layer and effectively eliminates the incubation layer, and then enhances the collection efficiency of the cell in the short wavelength region of the spectrum. The p/i interface defect density also decreases from 2.2 × 10^12cm^-2to 5.0 × 10^11cm^-2. This graded buffer layer allows to simplify the deposition process for the μc-Si：H solar cell application.

Analysis of Effect of Zn(O,S) Buffer Layer Properties on CZTS Solar Cell Performance Using AMPS

The Cu2ZnSnS4 （CZTS）-based solar cell is numerically simulated by a one-dimensional solar cell simulation soft- ware analysis of microelectronic and photonic structures （AMPS-1D）. The device structure used in the simulation is Al/ZnO：Al/nZn（O,S）/pCZTS/Mo. The primary motivation of this simulation work is to optimize the composition in the ZnO1-xSx buffer layer, which would yield higher conversion efficiency. By varying S/（S＋O） ratio x, the conduction band offset （CBO） at CZTS/Zn（O,S） interface can range from -0.23 eV to 1.06eV if the full range of the ratio is considered. The optimal CBO of 0.23eV can be achieved when the ZnO1-xSx buffer has an S/（S＋O） ratio of 0.6. The solar cell efficiency first increases with increasing sulfur content and then decreases abruptly for x〉 0.6, which reaches the highest value of 17.55% by our proposed optimal sulfur content x= 0.6. Our results provide guidance in dealing with the ZnO1-xSx buffer layer deposition for high efficiency CZTS solar cells.

Numerical Simulation of Varied Buffer Layer of Solar Cells Based on Cigs

Numerical simulation has been used to investigate the effect of different buffer?layer components on the performance of CuInGaSe2?solar cells?with SCAPS-1D?software. The main photovoltaic parameters of simulated devices: open-circuit?voltage (Voc), short-circuit current (Jsc), fill factor (FF), and conversion efficiency (h),?areanalysed as a function of thickness and temperature in the different buffer layers used. According to numerical simulation the highest conversion?efficiency (23%) of CIGS solar cell is reached for the CdS buffer layer. This?result is validated by experimental results?(20%). At 300 K, when the thickness?of?the buffer layer (CdS, ZnS, ZnSe,?InSe2) increases from 100 nm to 500?nm,?with the other parameters maintained constant, the efficiency decreases. When the temperature increases from 300 K to 400 K,?with the other parameters maintained?constant, both open circuit voltage and conversion efficiency also decrease.?The?effect of dual buffer layers of ZnS/CdS has also been analysed and his efficiency increases?of 3% than a single buffer CdS.

Investigation on Lanthanum Fluoride as a Novel Cathode Buffer Material Layer for the Enhancement of Stability and Performance of Organic Solar Cell

This article presents the investigation on very thin Lanthanum Fluoride (LaF3) layer as a new cathode buffer layer (CBL) for organic solar cell (OSC). OSCs were fabricated with poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) polymer blend at 1:1 ratio. Electron-beam evaporation at room temperature was used to deposit 3 and 5 nm thick LaF3 layer. A very smooth surface of LaF3 with an average roughness of 0.2 nm has been observed by the Atomic Force Microscope (AFM) that is expected to prevent diffusion of cathode metal ion through it and thereby enhance the lifetime and stability of OSC. Huge enhancement of JSC and VOC was also observed for 3 nm-thick LaF3 CBL. Several excellent features of the LaF3 layer such as, transporting electron through tunneling, blocking of holes to the cathode, minimizing recombination, protecting the photoactive polymer from ambient oxygen, and reducing degradation/oxidation of any low work function layer at the cathode interface, might have contributed to the performance enhancement of OSC. The experimental findings indicate the promise of LaF3 to be an excellent CBL material for OSC.

Effects of Annealing Conditions on ZnO Buffer Layer for Inverted Polymer Solar Cells

A solution-processed zinc oxide (ZnO) thin film as the buffer layer with optimized processes especially the annealing conditions for inverted polymer solar cells (PSCs) has been demonstrated. Firstly the thickness of ZnO buffer layer was optimized, and different annealing conditions including temperature and time have also been taken into consideration. And the best Power Conversion Efficiency (PCE) 3.434% was observed when the ZnO buffer layer was spin–coated at 1500 rpm and annealed at 275℃ for 5 min, and AFM results showed that morphology of this ZnO film has the best uniformity which was beneficial to form high quality polymer composite active layer.

Tin dioxide buffer layer-assisted efficiency and stability of wide-bandgap inverted perovskite solar cells

Inverted perovskite solar cells(IPSCs) have attracted tremendous research interest in recent years due to their applications in perovskite/silicon tandem solar cells. However, further performance improvements and long-term stability issues are the main obstacles that deeply hinder the development of devices. Herein, we demonstrate a facile atomic layer deposition(ALD) processed tin dioxide(SnO2) as an additional buffer layer for efficient and stable wide-bandgap IPSCs. The additional buffer layer increases the shunt resistance and reduces the reverse current saturation density, resulting in the enhancement of efficiency from 19.23% to 21.13%. The target device with a bandgap of 1.63 eV obtains open-circuit voltage of 1.19 V, short circuit current density of 21.86 mA/cm^(2), and fill factor of 81.07%. More importantly, the compact and stable SnO_(2) film invests the IPSCs with superhydrophobicity, thus significantly enhancing the moisture resistance. Eventually, the target device can maintain 90% of its initial efficiency after 600 h storage in ambient conditions with relative humidity of 20%–40% without encapsulation. The ALD-processed SnO_(2) provides a promising way to boost the efficiency and stability of IPSCs, and a great potential for perovskite-based tandem solar cells in the near future.

The properties of CdTe solar cells with ZnTe/ZnTe: Cu buffer layers

CdS/CdTe solar cells with ZnTe/ZnTe:Cu buffer layers were fabricated and studied.The energyband structure of it was analyzed.The C-V,I-V characteristics and the spectral response show that theZnTe/ZnTe:Cu buffer layers improve the back contact characteristic properties,the diode characteristicsof the forward junction and the short-wave spectral response of the CdTe solar cells.The ZnTe/ZnTe:Cubuffer layers affect the solar cell conversion efficiency and its fill factor.

Effect of H treatment on performance of HIT solar cells

Hydrogen is a ubiquitous element in semiconductor processing and particularly in amorphous and microcrystalline silicon where it plays a crucial role in the growth processes as well as in the material properties. Because of its low mass it can easily diffuse through the silicon network and leads to the passivation of dangling bonds but it may also play a role in the stabilization of metastable defects. Thus a lot of work has been devoted to the study of hydrogen diffusion, bonding and structure in disordered semiconductors. The sequence, deposition-exposure to H plasma-deposition was used to fabricate the microcrystalline emitter. A proper atomic H pretreatment of c-Si surface before depositions i layer was expected to clean the surface and passivatates the surface states, as a result improing the device parameters. In this study, H2 pretreatment of c-si surface was used at different time, power and temperature. It is found that a proper H pretreatment improves passivation of c-si surface and improves the device parameters by AFM and testing I-V.

Influence of small-molecule material on performance of polymer solar cells based on MEH-PPV:PCBM blend

In this work, the influence of a small-molecule material, tris（8-hydroxyquinoline） aluminum （Alq3）, on bulk heterojunction （BHJ） polymer solar cells （PSCs） is investigated in devices based on the blend of poly（2-methoxy-5-（2- ethylhexyloxy）-1,4-phenylenevinylene） （MEH-PPV） and [6,6]-phenyl-C61-butyric acid methyl ester （PCBM）. By doping Alq3 into MEH-PPV：PCBM solution, the number of MEH-PPV excitons can be effectively increased due to the energy transfer from Alq3 to MEH-PPV, which probably induces the increase of photocurrent generated by excitons dissociation. However, the low carrier mobility of Alq3 is detrimental to the efficient charge transport, thereby blocking the charge collection by the respective electrodes. The balance between photon absorption and charge transport in the active layer plays a key role in the performance of PSCs. For the case of 5 wt.% Alq3 doping, the device performance is deteriorated rather than improved as compared with that of the undoped device. On the other hand, we adopt Alq3 as a buffer layer instead of commonly used LiF. All the photovoltaic parameters are improved, yielding an 80% increase in power conversion efficiency （PCE） at the optimum thickness （1 nm） as compared with that of the device without any buffer layer. Even for the 5 wt.% Alq3 doped device, the PCE has a slight enhancement compared with that of the standard device after modification with 1 nm （or 2 nm） thermally evaporated Alq3. The performance deterioration of Alq3-doped devices can be explained by the low solubility of Alq3, which probably deteriorates the bicontinuous D-A network morphology; while the performance improvement of the devices with Alq3 as a buffer layer is attributed to the increased light harvesting, as well as blocking the hole leakage from MEH-PPV to the aluminum （Al） electrode due to the lower highest occupied molecular orbital （HOMO） level of Alq3 compared with that of MEH-PPV.

MoN_(x)薄膜制备及其在柔性不锈钢CIGS太阳电池中的应用

采用反应磁控溅射法制备MoN_(x)薄膜,研究N2流量对MoN_(x)薄膜的结构、形貌、元素组分和光电学特性的影响。通过XRD、SEM、紫外-可见分光光度计等测试,结果表明:当增大N2流量时,薄膜晶相由Mo相向Mo2N相逐渐发生改变,且薄膜的反射率也发生变化,而后利用MoN_(x)薄膜作为抑制Fe等杂质向CIGS薄膜扩散的阻挡层;XRD、SEM结果表明,MoN_(x)薄膜的引入不会影响Mo薄膜、CIGS薄膜晶体结构和形貌;此外,二次离子质谱(SIMS)表明,MoN_(x)阻挡层显著降低了CIGS薄膜中Fe的浓度,最终,将柔性CIGS太阳电池的光电转换效率由10%提升至12.5%。

Theoretical simulation of performances in CIGS thin-film solar cells with cadmiumfree buffer layer

Copper indium gallium selenium （CIGS） thin film solar cells have become one of the hottest topics in solar energy due to their high photoelectric transformation efficiency. To real applications, CIGS thin film is covered by the buffer layer and absorption layer. Traditionally, cadmium sulfide （CdS） is inserted into the middle of the window layer （ZnO） and absorption layer （CIGS） as a buffer layer. However, the application of the GIGS/CdS thin film solar cells has been limited because of the environmental pollution resulting from the toxic cadmium atom. Although zinc sulfide （ZnS） has been proposed to be one of the candidates, the performance of such battery cells has not been investigated. Here, in this paper, we systematically study the possibility of using zinc sulfide （ZnS） as a buffer layer. By including the effects of thickness, concentration of a buffer layer, intrinsic layer and the absorbing layer, we find that photoelectric transformation efficiency of ZnO/ZnS（n）/CIGS（i）/CIGS（p） solar cell is about 17.22%, which is qualified as a commercial solar cell. Moreover, we also find that the open-circuit voltage is -0.60 V, the short-circuit current is -36.99 mA/cm2 and the filled factor is -77.44%. Therefore, our results suggest that zinc sulfide may be the potential candidate of CdS as a buffer layer.

界面层对CIGS薄膜太阳电池电性能影响的数值模拟研究

通过在铜铟镓硒(CIGS)薄膜太阳电池中分别插入RbInSe_(2)薄膜和MoSe_(2)薄膜作为界面层,设计出新的电池结构,然后使用模拟软件wxAMPS研究了界面层对CIGS薄膜太阳电池电性能的影响。研究结果表明:RbInSe_(2)薄膜对CIGS薄膜太阳电池电性能的提高效果不明显,且随着RbInSe_(2)薄膜厚度的增加,电池电性能呈先升高后降低的趋势。MoSe_(2)薄膜对CIGS薄膜太阳电池的电性能有显著的提高作用,主要原因是该薄膜与CIGS薄膜构成的异质结在电池内部附加了一个电场。该电场能够将向MoSe_(2)薄膜运动的电子“反射”回CIGS薄膜中,降低载流子的界面复合速度,进而提高光生电流。以分析获得的最优参数进行数值模拟,同时插入MoSe_(2)薄膜和RbInSe_(2)薄膜的CIGS薄膜太阳电池的最高光电转换效率可达25.0%,这为实验室及实际生产制备出高效CIGS薄膜太阳电池提供了一条可能的技术路径。