Ultralong Carrier Lifetime Exceeding 20 µs in Lead Halide Perovskite Film Enable Efficient Solar Cells

• Published in: Advanced materials (Weinheim) 2023-07, Vol.35 (28), p.e2212126-n/a
• Main Authors: Guo, Jiahao, Wang, Bingzhe, Lu, Di, Wang, Ting, Liu, Tingting, Wang, Rui, Dong, Xiyue, Zhou, Tong, Zheng, Nan, Fu, Qiang, Xie, Zengqi, Wan, Xiangjian, Xing, Guichuan, Chen, Yongsheng, Liu, Yongsheng
• Format: Article
• Language: English
• Subjects: 2D/3D perovskite; Carrier lifetime; Crystal defects; device engineering; Electronic structure; Grain boundaries; Lead compounds; Lifetime; Materials science; Metal halides; Optoelectronics; Perovskites; Photovoltaic cells; Solar cells; trap density
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202212126

The carrier lifetime is one of the key parameters for perovskite solar cells (PSCs). However, it is still a great challenge to achieve long carrier lifetimes in perovskite films that are comparable with perovskite crystals owning to the large trap density resulting from the unavoidable defects in grain boundaries and surfaces. Here, by regulating the electronic structure with the developed 2‐thiopheneformamidinium bromide (ThFABr) combined with the unique film structure of 2D perovskite layer caped 2D/3D polycrystalline perovskite film, an ultralong carrier lifetime exceeding 20 µs and carrier diffusion lengths longer than 6.5 µm are achieved. These excellent properties enable the ThFA‐based devices to yield a champion efficiency of 24.69% with a minimum VOC loss of 0.33 V. The unencapsulated device retains ≈95% of its initial efficiency after 1180 h by max power point (MPP) tracking under continuous light illumination. This work provides important implications for structured 2D/(2D/3D) perovskite films combined with unique FA‐based spacers to achieve ultralong carrier lifetime for high‐performance PSCs and other optoelectronic applications. By regulating the electronic structure with ThFABr, an ultralong carrier lifetime exceeding 20 µs and carrier diffusion lengths longer than 6.5 µm is achieved in 2D/3D polycrystalline perovskite films. These excellent properties enable the ThFA‐based devices yielding a champion efficiency of 24.69% and a high VOC of 1.21 V, coupled with significantly improved operational stability.