Li Fengzhu, Deng Xiang, Qi Feng, Li Zhen, Liu Danjun, Shen Dong, Qin Minchao, Wu Shengfan, Lin Francis, Jang Sei-Hum, Zhang Jie, Lu Xinhui, Lei Dangyuan, Lee Chun-Sing, Zhu Zonglong, Jen Alex K-Y
Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong.
J Am Chem Soc. 2020 Nov 25;142(47):20134-20142. doi: 10.1021/jacs.0c09845. Epub 2020 Nov 15.
Passivating surface and bulk defects of perovskite films has been proven to be an effective way to minimize nonradiative recombination losses in perovskite solar cells (PVSCs). The lattice interference and perturbation of atomic periodicity at the perovskite surfaces often significantly affect the material properties and device efficiencies. By tailoring the terminal groups on the perovskite surface and modifying the surface chemical environment, the defects can be reduced to enhance the photovoltaic performance and stability of derived PVSCs. Here, we report a rationally designed bifunctional molecule, piperazinium iodide (), containing both RNH and RNH groups on the same six-membered ring, behaving both as an electron donor and an electron acceptor to react with different surface-terminating ends on perovskite films. The resulting perovskite films after defect passivation show released surface residual stress, suppressed nonradiative recombination loss, and more -type characteristics for sufficient energy transfer. Consequently, charge recombination is significantly suppressed to result in a high open-circuit voltage () of 1.17 V and a reduced loss of 0.33 V. A very high power conversion efficiency (PCE) of 23.37% (with 22.75% certified) could be achieved, which is the highest value reported for inverted PVSCs. Our work reveals a very effective way of using rationally designed bifunctional molecules to simultaneously enhance the device performance and stability.
钝化钙钛矿薄膜的表面和体缺陷已被证明是减少钙钛矿太阳能电池（PVSCs）中非辐射复合损失的有效方法。钙钛矿表面的晶格干扰和原子周期性扰动常常会显著影响材料性能和器件效率。通过调整钙钛矿表面的端基并改变表面化学环境，可以减少缺陷，从而提高衍生PVSCs的光伏性能和稳定性。在此，我们报道了一种合理设计的双功能分子，碘化哌嗪鎓（），在同一个六元环上同时含有RNH和RNH基团，既作为电子供体又作为电子受体与钙钛矿薄膜上不同的表面终止端反应。缺陷钝化后的钙钛矿薄膜显示出释放的表面残余应力、抑制的非辐射复合损失以及更多的 -型特征以实现充分的能量转移。因此，电荷复合被显著抑制，从而产生了1.17 V的高开路电压（）和0.33 V的降低的 损失。可以实现23.37%（经认证为22.75%）的非常高的功率转换效率（PCE），这是倒置PVSCs报道的最高值。我们的工作揭示了一种使用合理设计的双功能分子同时提高器件性能和稳定性的非常有效的方法。
