Dual molecular bridges at perovskite heterointerfaces for efficient inverted solar cells
Qing Lian, Lina Wang, Guoliang Wang, Guojun Mi, Bowei Li, Joel A. Smith, Pietro Caprioglio, Manuel Kober‐Czerny, Deng Wang, Qiming Yin, Jiong Yang, Sibo Li, Liang Xiao, Shaokuan Gong, Dongyang Li, Hanlin Hu, Xihan Chen, Xugang Guo, Longbin Qiu, Baomin Xu, Gang Li, Anita Ho‐Baillie, Wei Zhang, Guangfu Luo, Henry J. Snaith, Chun Cheng
Abstract
Utilizing molecular bridges presents a promising means to enhance the performance of perovskite solar cells (PSCs). However, concurrently bridging the perovskite absorber and its two adjacent interfaces remains a significant challenge that is yet to be achieved. Here, we construct dual molecular bridges at perovskite heterointerfaces, enabled by a self-organizing additive of 4-fluoro-phenethylammonium formate (4-F-PEAFa) and a synthesized hole transporter of [2-(7H-dibenzo[c, g]carbazol-7-yl)ethyl]phosphonic acid (DBZ-2PACz). The molecular bridges spanning two interfaces lead to the formation of an 'integral carrier transport pathway', mitigating both non-radiative recombination and charge-transport losses in the fabricated PSC devices. We thus achieve a champion power conversion efficiency (PCE) of 26.0% (25.6% certified) in inverted PSCs, accompanied by an exceptionally high fill factor of 0.87 (maximum 0.88 from the certified devices, 97% of its Shockley-Queisser limit) and a low ideality factor of 1.06. The unencapsulated devices retain 96% of their PCEs after aging at 85°C for 2200 h and 90% after maximum power point tracking at an elevated temperature of 50°C for 973 h.