Li, M.; Zuo, W.; Wang, Z.; Li, Y.; Wang, Q.; Wang, K.; Zhou, M.; Köbler, H.; Halbig, E. C.; Eigler, S.; Yang, Y.; Gao, X.; Wang, Z.; Li, Y.; Abate, A.: Ultrathin nanosheets of oxo-functionalized graphene inhibit the ion migration in perovskite solar cells. Advanced Energy Materials 10 (2020), p. 1902653/1-8
10.1002/aenm.201902653
Open Access Version
Abstract:
Mixed cation/halide perovskites have led to a significant increase in the efficiency and stability of perovskite solar cells. However, mobile ionic defects inevitably exacerbate the photoinduced phase segregation and self-decomposition of the crystal structure. Herein, ultrathin two-dimensional nanosheets of oxo-functionalized graphene/dodecylamine (oxo-G/DA) are used to solve ion migration in cesium (Cs)-formamidinium (FA)-methylammonium (MA) triple cation-base perovskites. Based on the superconducting carbon skeleton and functional groups that provide lone pairs of electrons on it, the ultra-thin two-dimensional network structure can tight fit on the crystals and wrap them, isolate them and thus reduce the migration of ions within the built-in electric field of the perovskite film. As evidence of the formation of sharp crystals with different orientation within the perovskite film, we observed moiré fringes in transmission electron microscopy. Thus, we report a champion device with a power conversion efficiency (PCE) of 21.1% (the efficiencies distribution is 18.8±1.7%), and a remarkable fill factor of 81%, with reduced hysteresis and improved long-term stability. This work provides a simple method for the improvement of the structural stability of perovskite in solar cells.