全黄铜矿CuGaSe_(2)/CuInSe_(2)两端叠层太阳能电池的顶端设计与优化

Top cell design and optimization of all-chalcopyrite CuGaSe_(2)/CuInSe_(2) two-terminal tandem solar cells

近年来单结太阳能电池的光电转换效率逐步提高,但其最高效率受到Shockley-Queisser (SQ)极限的限制.为了超越SQ极限,学者们提出了叠层太阳能电池.本工作结合第一性原理计算和SCAPS-1D器件模拟对黄铜矿化合物CuGaSe_(2)/CuInSe_(2)叠层太阳能电池进行了系统的理论研究.首先通过第一性原理计算获取了CuGaSe_(2) (CGS)的微观电子结构、缺陷特性及对应的宏观性能参数,作为后续器件模拟CGS太阳能电池的输入参数.随后采用SCAPS-1D软件分别对单结CGS与CuInSe_(2) (CIS)太阳能电池进行了仿真模拟.单结CIS太阳能电池的模拟结果与实验值具有良好的一致性.对单结CGS电池而言,在短路电流(J_(sc))最高的生长环境下进一步模拟发现,将电子传输层(ETL)换为ZnSe后可提高CGS太阳能电池的开路电压(V_(oc))和PCE.最后,将优化后的CGS与CIS太阳能电池进行了两端(2T)单片串联的器件模拟,结果显示在生长环境为富Cu、富Ga、贫Se,生长温度为700 K时,2T单片CGS/CIS叠层太阳能电池的PCE最高为28.91%,高于当前最高的单结太阳能电池效率,展现出良好的应用前景.

Solar cells have attracted much attention,for they can convert solar energy directly into electric energy,and have been widely utilized in manufacturing industry and people’s daily life.Although the power conversion efficiency(PCE)of single-junction solar cells has gradually improved in recent years,its maximum efficiency is still limited by the Shockley-Queisser(SQ)limit of single-junction solar cells.To exceed the SQ limit and further obtain high-efficiency solar cells,the concept of tandem solar cells has been proposed.In this work,the chalcopyrite CuGaSe_(2)/CuInSe_(2) tandem solar cells are studied systematically in theory by combining first-principle calculations and SCAPS-1D device simulations.Firstly,the electronic structure,defect properties and corresponding macroscopic performance parameters of CuGaSe_(2)(CGS)are obtained by first-principles calculations,and are used as input parameters for subsequent device simulations of CGS solar cells.Then,the single-junction CGS and CuInSe2(CIS)solar cells are simulated by using SCAPS-1D software,respectively.The simulation results for the single junction CIS solar cells are in good agreement with the experimental values.For single-junction CGS cells,the device simulations reveal that the CGS single-junction solar cells have the highest short-circuit current(Jsc)and PCE under the Cu-rich,Ga-rich and Se-poor chemical growth condition.Further optimization in the growth environment with the highest short circuit current(Jsc)shows that the open-circuit voltage(Voc)and PCE of CGS solar cells can be improved by replacing the electron transport layer(ETL)with ZnSe.Finally,after the optimized CGS and CIS solar cells are connected in series with two-terminal(2T)monolithic tandem solar cell,the device simulation results show that under the growth temperature of 700 K and the growth environment of Cu-rich,Ga-rich,and Se-poor,with ZnSe serving as the ETL,the CGS thickness of 2000 nm and the CIS thickness of 1336 nm,the PCE of 2T monolithic CGS/CIS tandem solar cell can reach 28.91%,which is higher than the ever-recorded efficiency of the current single-junction solar cells,and shows that this solar cell has a good application prospect.