Dong Wei, Qiao Wencheng, Xiong Shaobing, Yang Jianming, Wang Xuelu, Ding Liming, Yao Yefeng, Bao Qinye
Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, 200241, People's Republic of China.
School of Physics and Electronic Science, East China Normal University, Shanghai, 200241, People's Republic of China.
Nanomicro Lett. 2022 Apr 19;14(1):108. doi: 10.1007/s40820-022-00854-0.
Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells. However, so far the interaction mechanisms between passivating additive and perovskite are not well understood. Here, we report the atomic-scale interaction of surface passivating additive 2,2-difluoroethylammonium bromine (2FEABr) on the MAPbI. It is found that the bulky 2FEA cations tend to distribute at film surface, while the Br anions diffuse from surface into bulk. A combination of F, Pb, and H solid-state NMR further reveal the Br anions' partial substitution for the I sites, the restricted motion of partial MA cations, and the firmed perovskite lattices, which would improve charge transport and stability of the perovskite films. Optical spectroscopy and ultraviolet photoelectron spectroscopy demonstrate that the 2FEABr induced surface passivation and energetic modification suppress the nonradiative recombination loss. These findings enable the efficiency of the p-i-n structured PSC significantly increasing from 19.44 to 21.06%, accompanied by excellent stability. Our work further establishes more knowledge link between passivating additive and PSC performance.
通过后处理进行表面钝化是提高钙钛矿太阳能电池功率转换效率和运行稳定性的重要策略。然而，到目前为止，钝化添加剂与钙钛矿之间的相互作用机制尚未得到很好的理解。在此，我们报道了表面钝化添加剂2,2-二氟乙铵溴（2FEABr）在MAPbI₃上的原子尺度相互作用。研究发现，体积较大的2FEA阳离子倾向于分布在薄膜表面，而Br⁻阴离子则从表面扩散到体相中。F、Pb和H的固态核磁共振组合进一步揭示了Br⁻阴离子对I位点的部分取代、部分MA阳离子的受限运动以及钙钛矿晶格的稳固，这将改善钙钛矿薄膜的电荷传输和稳定性。光谱学和紫外光电子能谱表明，2FEABr诱导的表面钝化和能量改性抑制了非辐射复合损失。这些发现使p-i-n结构的PSC效率从19.44%显著提高到21.06%，同时具有出色的稳定性。我们的工作进一步建立了钝化添加剂与PSC性能之间更多的知识联系。
