(558bb) Efficient Ambient-Air-Stable HTM-Free Carbon-Based Perovskite Solar Cells

Hole transport material (HTM)-free carbon-based perovskite solar cells (C-PSCs) are arguably the most promising for commercialization applications because of their low cost and excellent stability. However, the most commonly used 3D MAPbI3 photoabsorber is ambient-unstable and incompatible with the low-cost mass-production of C-PSCs. In this work, we fabricate a series of 2D–3D hybrid (EA)2(MA)n-1PbnI3n+1 perovskites in C-PSCs based on the proven operational stability of 2D perovskites. It exhibits extremely improved ambient and photo-stability under 60 day-ambient conditions. The HTM-free C-PSCs with a structure of ITO/C60/(EA)2(MA)n-1PbnI3n+1/C retain outstanding power conversion efficiency over 11.88%. By tuning the stoichiometry of (EA)2(MA)n-1PbnI3n+1 to n = 6, the n6-2D device maintains a long-term stability of 93% under ambient conditions after 2160 hours, a thermal stability of 80% after heating at 80 C over 100 hours, and a photo-stability of 92% under continuous 1 sun illumination over 300 hours, which are apparently superior to those of the MAPbI3 device (i.e. ambient stability of 73%; thermal stability of 9%; photo-stability of 67% after 83 hours). Our work provides a simple and operational avenue to advance perovskite devices toward commercial applications.