Song Yanping, Sun Huanhuan, Yao Bin, Li Yongfeng, Ding Zhanhui, Qin Wei, Zhang Zhenzhong, Zhang Ligong, Zhao Haifeng, Pan Daocheng
State Key Laboratory of Superhard Materials and Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012, P. R. China.
State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No. 3888 Dongnanhu Road, Changchun 130033, P. R. China.
ACS Appl Mater Interfaces. 2020 Aug 26;12(34):38163-38174. doi: 10.1021/acsami.0c10561. Epub 2020 Aug 12.
For further efficiency improvement in kesterite-type CuZnSn(S,Se) (CZTSSe) solar cells, it is essential to address the carrier recombination issue at the back electrode interface (BEI) caused by the undesirable built-in potential orientation toward an absorber as an -MoSe interfacial layer formed. In this regard, back surface field (BSF) incorporation, i.e., field-effect passivation, shows promise for dealing with this issue due to its positive effect in decreasing recombination at the BEI. In this study, the BSF was realized with the p-type conduction transition in interfacial layer MoSe by incorporating Nb into the back electrode. The BSF width can be tuned via modulating the carrier concentration of the absorber, which has been demonstrated by capacitance-voltage characterization. A beyond 7% efficiency BSF-applied CZTSSe solar cell is prepared, and the effects of a tunable BSF and the mechanism underpinning device performance improvement have been investigated in detail. The wider BSF distribution in the absorber induces a decrease in reverse saturation current density () due to the stronger BSF effect in suppressing BEI recombination. As a result, an accompanying increase in open-circuit voltage () and short-circuit current density () is achieved as compared to the BSF-free case. This study offers an alternative strategy to address the BEI recombination issue and also broadens the interface passivation research scope of potentially competitive kesterite solar cells.
为了进一步提高铜锌锡硫硒（CZTSSe）太阳能电池的效率，解决由作为-MoSe界面层形成时朝向吸收体的不良内建电势取向所导致的背电极界面（BEI）处的载流子复合问题至关重要。在这方面，背表面场（BSF）的引入，即场效应钝化，因其在降低BEI处复合方面的积极作用而显示出解决该问题的前景。在本研究中，通过将Nb掺入背电极，利用界面层MoSe中的p型导电转变实现了BSF。通过电容-电压表征已证明，可以通过调节吸收体的载流子浓度来调整BSF宽度。制备了效率超过7%的应用BSF的CZTSSe太阳能电池，并详细研究了可调BSF的作用以及器件性能提高的潜在机制。由于更强的BSF效应抑制了BEI处的复合，吸收体中更宽的BSF分布导致反向饱和电流密度（）降低。结果，与无BSF的情况相比，开路电压（）和短路电流密度（）随之增加。本研究提供了一种解决BEI复合问题的替代策略，也拓宽了具有潜在竞争力的硫铜矿太阳能电池的界面钝化研究范围。
