Yang Jianming, Xiong Shaobing, Qu Tianyi, Zhang Yuexing, He Xiaoxiao, Guo Xuewen, Zhao Qiuhua, Braun Slawomir, Chen Jinquan, Xu Jianhua, Li Yanqing, Liu Xianjie, Duan Chungang, Tang Jianxin, Fahlman Mats, Bao Qinye
Key Laboratory of Polar Materials and Devices, Department of Optoelectronics , East China Normal University , Shanghai 200241 , P.R. China.
Institute of Functional Nano & Soft Materials , Soochow University , Suzhou 215123 , P. R. China.
ACS Appl Mater Interfaces. 2019 Apr 10;11(14):13491-13498. doi: 10.1021/acsami.9b01740. Epub 2019 Mar 29.
The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.
金属卤化物钙钛矿太阳能电池的快速发展为可再生能源领域开启了新篇章。高质量的钙钛矿薄膜作为活性层对于高效率和长期稳定性都至关重要。在此，通过将成本极低的绿色聚合物乙基纤维素（EC）引入钙钛矿层，制备出了晶粒尺寸增大且缺陷密度降低的钙钛矿薄膜。EC的添加引发了EC与钙钛矿之间的氢键相互作用，钝化了晶界处的电荷缺陷陷阱。EC的长链进一步充当钙钛矿结构的支架，消除了薄膜制备过程中退火诱导的晶格应变。添加了EC的所得器件的平均功率转换效率从17.11%显著提高到19.27%，且所有器件参数均有所改善。发现滞后指数从0.081降至0.027，降低了三倍，这归因于离子迁移和表面电荷俘获受到抑制。此外，EC对缺陷的钝化显著提高了钙钛矿薄膜的环境稳定性，使得器件在45%相对湿度的环境空气中放置30天后仍能保持其初始效率的80%，而没有EC的原始器件则完全降解。这项工作为钝化缺陷提供了一条低成本且绿色的途径，提高了钙钛矿太阳能电池的效率和运行稳定性。
