The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization...The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization of environmentally friendly and efficient CZTSSe solar cells. The Zn1-xMgxO(ZnMgO) and Zn1-xSnxO(ZnSnO) alternate buffer layers are studied in this study using the simulation package solar cell capacitance simulator(SCAPS-1D) numerical simulation model, and the theoretical analysis is further verified by the results of the experiments. We simulate the performance of CZTSSe/ZnXO(X = Mg/Sn) heterojunction devices with different Mg/(Zn+Mg) and Sn/(Zn+Sn) ratios and analyze the intrinsic mechanism of the effect of conduction band offsets(CBO) on the device performance. The simulation results show that the CZTSSe/ZnXO(X = Mg/Sn) devices achieve optimal performance with a small “spike” band or “flat” band at Mg and Sn doping concentrations of 0.1 and 0.2, respectively. To investigate the potential of Zn_(0.9)Mg_(0.1O) and Zn_(0.8)Sn_(0.2)O as alternative buffer layers, carrier concentrations and thicknesses are analyzed. The simulation demonstrates that the Zn0.9Mg0.1O device with low carrier concentration has a high resistivity, serious carrier recombination, and a greater impact on performance from thickness variation. Numerical simulations and experimental results show the potential of the ZnSnO buffer layer as an alternative to toxic CdS, and the ZnMgO layer has the limitation as a substitute buffer layer. This paper provides the theoretical basis and experimental proof for further searching for a suitable flexible CZTSSe Cd-free buffer layer.展开更多
Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recom...Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recombination of CZTSSe/CdS heterojunction interface.We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils.The efficiency of the device is improved from 5.7%to 6.86%by highquality junction interface.Furthermore,aiming at the S loss of CdS film,the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality.The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05%efficiency with a VOC of 0.44 V at an optimized S source concentration of 0.68 mol/L.Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the VOCdeficit.For the CZTSSe device bending characteristics,the device efficiency is almost constant after1000 bends,manifesting that the CZTSSe device has an excellent mechanical flexibility.The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 62074037 and 52002073)the Fund from the Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China (Grant No. 2021ZZ124)。
文摘The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization of environmentally friendly and efficient CZTSSe solar cells. The Zn1-xMgxO(ZnMgO) and Zn1-xSnxO(ZnSnO) alternate buffer layers are studied in this study using the simulation package solar cell capacitance simulator(SCAPS-1D) numerical simulation model, and the theoretical analysis is further verified by the results of the experiments. We simulate the performance of CZTSSe/ZnXO(X = Mg/Sn) heterojunction devices with different Mg/(Zn+Mg) and Sn/(Zn+Sn) ratios and analyze the intrinsic mechanism of the effect of conduction band offsets(CBO) on the device performance. The simulation results show that the CZTSSe/ZnXO(X = Mg/Sn) devices achieve optimal performance with a small “spike” band or “flat” band at Mg and Sn doping concentrations of 0.1 and 0.2, respectively. To investigate the potential of Zn_(0.9)Mg_(0.1O) and Zn_(0.8)Sn_(0.2)O as alternative buffer layers, carrier concentrations and thicknesses are analyzed. The simulation demonstrates that the Zn0.9Mg0.1O device with low carrier concentration has a high resistivity, serious carrier recombination, and a greater impact on performance from thickness variation. Numerical simulations and experimental results show the potential of the ZnSnO buffer layer as an alternative to toxic CdS, and the ZnMgO layer has the limitation as a substitute buffer layer. This paper provides the theoretical basis and experimental proof for further searching for a suitable flexible CZTSSe Cd-free buffer layer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074037,61574038,51961165108,and 51972332)the Natural Science Foundation of Fujian Province,China(Grant No.2017J01503)+2 种基金the Education and Scientific Research Project of Fujian Province,China(Grant No.JAT190010)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment,China(Grant No.SKLPEE-202011)Fuzhou University,China。
文摘Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recombination of CZTSSe/CdS heterojunction interface.We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils.The efficiency of the device is improved from 5.7%to 6.86%by highquality junction interface.Furthermore,aiming at the S loss of CdS film,the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality.The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05%efficiency with a VOC of 0.44 V at an optimized S source concentration of 0.68 mol/L.Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the VOCdeficit.For the CZTSSe device bending characteristics,the device efficiency is almost constant after1000 bends,manifesting that the CZTSSe device has an excellent mechanical flexibility.The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.
