Liu Xin, She Xingchen, Wang Lang, Li Wei, Zhang Wen, Wang Shu, Wangyang Peihua, Wang Zhijun, Li Jie, Cui Xumei, Lan Mu, Liu Liqin, Sun Hui, Zhang Jun, Yang Dingyu
College of Optoelectronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China.
Guangxi Key Laboratory of Precision Navigation Technology and Application, Guilin University of Electronic Technology, Guilin 541004, China.
J Chem Phys. 2024 Mar 7;160(9). doi: 10.1063/5.0192041.
All-inorganic CsPbI2Br inverted perovskite solar cells (PSCs) have drawn increasing attention because of their outstanding thermal stability and compatible process with tandem cells. However, relatively low open circuit voltage (Voc) has lagged their progress far behind theoretical limits. Herein, we introduce phenylmethylammonium iodide and 4-trifluoromethyl phenylmethylammonium iodide (CFPMAI) on the surface of a CsPbI2Br perovskite film and investigate their passivation effects. It is found that CFPMAI with a -CF3 substituent significantly decreases the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions and effectively suppresses the non-radiative recombination in the resulting PSC. In addition, CFPMAI surface passivation facilitates the optimization of energy-level alignment at the CsPbI2Br perovskite/[6,6]-phenyl C61 butyric acid methyl ester interface, resulting in improved charge extraction from the perovskite to the charge transport layer. Consequently, the optimized inverted CsPbI2Br device exhibits a markedly improved champion efficiency of 14.43% with a Voc of 1.12 V, a Jsc of 16.31 mA/cm2, and a fill factor of 79.02%, compared to the 10.92% (Voc of 0.95 V) efficiency of the control device. This study confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.
全无机CsPbI₂Br倒置钙钛矿太阳能电池（PSC）因其出色的热稳定性以及与串联电池兼容的工艺而受到越来越多的关注。然而，相对较低的开路电压（Voc）使其进展远远落后于理论极限。在此，我们在CsPbI₂Br钙钛矿薄膜表面引入碘化苯甲铵和4-三氟甲基碘化苯甲铵（CFPMAI），并研究它们的钝化效果。研究发现，带有-CF₃取代基的CFPMAI通过与配位不足的Pb²⁺离子形成相互作用，显著降低了钙钛矿薄膜的陷阱密度，并有效抑制了所得PSC中的非辐射复合。此外，CFPMAI表面钝化有助于优化CsPbI₂Br钙钛矿/[6,6]-苯基C61丁酸甲酯界面处的能级排列，从而改善从钙钛矿到电荷传输层的电荷提取。因此，优化后的倒置CsPbI₂Br器件表现出显著提高的冠军效率，为14.43%，Voc为1.12 V，Jsc为16.31 mA/cm²，填充因子为79.02%，而对照器件的效率为10.92%（Voc为0.95 V）。这项研究证实了表面钝化分子上的取代基对于有效钝化缺陷和优化能级，特别是提高Voc的重要性。
