A penetrated 2D/3D hybrid heterojunction for high-performance perovskite solar cells

Abstract

Organic–inorganic hybrid lead halide perovskite solar cells (PSCs) attracted tremendous interest due to their excellent photovoltaic performance, but they still suffer from the poor long-term stability. Here, a penetrated 2D/3D heterojunction strategy is developed to stabilize the crystal structure at both the surface as well as grain boundaries and suppress non-radiative recombination. The organic halide with a large cation, namely dimethylammonium iodide (DMAI), was reported to achieve such a penetrated 2D/3D heterojunction through a simple post-treatment approach. Under this circumstance, the efficiency of Cs_0.05FA_0.85MA_0.10Pb(I_0.90Br_0.10)₃ PSCs was improved from 19.83% to ∼22% due to the significantly increased open-circuit voltage (V_oc). In addition, we demonstrated the versatility of such a strategy in Cs_0.05FA_0.85MA_0.10Pb(I_0.97Br_0.03)₃ PSCs, leading to a champion efficiency approaching 23%. More importantly, the penetrated 2D/3D heterojunction can effectively protect the underlying 3D perovskite from moisture invasion. After ageing in air for 1000 hours, the device based on the 2D/3D heterojunction retained 80% of its initial efficiency, while the control device only maintained 57%.