Wang Han, Cheng Guanghui, Xie Jiangsheng, Zhao Shenghe, Qin Minchao, Chan Christopher C S, Qiu Yongcai, Chen Guangxu, Duan Chunhui, Wong Kam Sing, Wang Jiannong, Lu Xinhui, Xu Jianbin, Yan Keyou
Department of Physics , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , P. R. China.
School of Environment and Energy, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510006 , P. R. China.
ACS Appl Mater Interfaces. 2019 Jan 23;11(3):2935-2943. doi: 10.1021/acsami.8b17030. Epub 2019 Jan 8.
Multicomponent quasi-two-dimensional perovskites (Q-2DPs) have efficient luminescence and improved stability, which are highly desirable for light-emitting diode and perovskite solar cell (PSC). However, the lack of radiative recombination at room temperature is still not well understood and the performance of PSC is not good enough as well. The open-circuit voltage ( V) is even lower than that of three-dimensional (3D) PSC with a narrower band gap. In this work, we study the energy transfer of excitons between their multiple components by time-resolved photoluminescence and find that charge transfer from high-energy states to low-energy state is gradually suppressed during elevating temperature owing to trap-mediated recombination. This may reveal the bottleneck of luminescence at room temperature in Q-2DPs, leading to large photovoltage loss in 2D PSC. Therefore, we develop a p-i-n bulk heterojunction (BHJ) structure to reduce the nonradiative recombination and obtain high V of 1.18 V for (PMA)MAPbICl (33.3% PMA) BHJ device, much higher than that of the planar counterparts. The enhanced efficiency is attributed to the improved exciton dissociation via BHJ interface. Our results provide an important step toward high V and stable 2D PSCs, which could be used for tandem solar cell and colorful photovoltaic windows.
多组分准二维钙钛矿（Q-2DPs）具有高效的发光性能和更高的稳定性，这对于发光二极管和钙钛矿太阳能电池（PSC）来说是非常理想的。然而，室温下缺乏辐射复合的原因仍未得到很好的理解，并且PSC的性能也不够理想。其开路电压（V）甚至低于带隙更窄的三维（3D）PSC。在这项工作中，我们通过时间分辨光致发光研究了激子在其多个组分之间的能量转移，发现由于陷阱介导的复合，在升温过程中从高能态到低能态的电荷转移逐渐受到抑制。这可能揭示了Q-2DPs在室温下发光的瓶颈，导致二维PSC中出现较大的光电压损失。因此，我们开发了一种p-i-n体异质结（BHJ）结构以减少非辐射复合，并使（PMA）MAPbICl（33.3% PMA）BHJ器件获得了1.18 V的高开路电压，远高于平面结构的对应器件。效率的提高归因于通过BHJ界面改善了激子解离。我们的结果为实现高开路电压和稳定的二维PSC迈出了重要一步，这可用于串联太阳能电池和彩色光伏窗。
