Li Zihao, Sun Anxin, Zheng Yiting, Zhuang Rongshan, Wu Xueyun, Tian Congcong, Tang Chen, Liu Yuan, Ouyang Beilin, Du Jiajun, Li Ziyi, Cai Jingyu, Wu Xiling, Chen Jinling, Hua Yong, Chen Chun-Chao
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 20024, P. R. China.
Yunnan Key Laboratory for Micro/Nano Materials & Technology, School of Materials and Energy, Yunnan University, Kunming, 650091, P. R. China.
Small Methods. 2024 Dec;8(12):e2400425. doi: 10.1002/smtd.202400425. Epub 2024 Apr 9.
While the 2D/3D heterojunction is an effective method to improve the power conversion efficiency (PCE) of perovskite solar cells (PSCs), carriers are often confined in the quantum wells (QWs) due to the unique structure of 2D perovskite, which makes the charge transport along the out-of-plane direction difficult. Here, a 2D/3D ferroelectric heterojunction formed by 4,4-difluoropiperidine hydrochloride (2FPD) in inverted PSCs is reported. The enriched 2D perovskite (2FPD)PbI layer with n = 1 on the perovskite surface exhibits ferroelectric response and has oriented dipoles along the out-of-plane direction. The ferroelectricity of the oriented dipole layer facilitates the enhancement of the built-in electric field (1.06 V) and the delay of the cooling process of hot carriers, reflected in the high carrier temperature (above 1400 K) and the prolonged photobleach recovery time (139.85 fs, measured at bandgap), improving the out-of-plane conductivity. In addition, the alignment of energy levels is optimized and exciton binding energy (32.8 meV) is reduced by changing the dielectric environment of the surface. Finally, the 2FPD-treated PSCs achieve a PCE of 24.82% (certified: 24.38%) with the synergistic effect of ferroelectricity and defect passivation, while maintaining over 90% of their initial efficiency after 1000 h of maximum power point tracking.
虽然二维/三维异质结是提高钙钛矿太阳能电池（PSC）功率转换效率（PCE）的有效方法，但由于二维钙钛矿的独特结构，载流子通常被限制在量子阱（QW）中，这使得电荷沿面外方向传输变得困难。在此，报道了一种由盐酸4,4-二氟哌啶（2FPD）在倒置PSC中形成的二维/三维铁电异质结。钙钛矿表面n = 1的富集二维钙钛矿（2FPD）PbI层表现出铁电响应，并具有沿面外方向的取向偶极子。取向偶极子层的铁电性有助于增强内建电场（1.06 V）并延迟热载流子的冷却过程体现在高载流子温度（高于1400 K）和延长的光漂白恢复时间（139.85 fs，在带隙处测量）上，从而提高面外电导率。此外，通过改变表面的介电环境优化了能级排列并降低了激子结合能（32.8 meV）。最后，经2FPD处理的PSC在铁电性和缺陷钝化的协同作用下实现了24.82%的PCE（认证值：24.38%），同时在最大功率点跟踪1000小时后仍保持其初始效率的90%以上。
