Abstract
The intrinsic instability of hybrid perovskite materials induced by defect states arises as one major challenge hampering the commercialization of perovskite solar cells (PSCs). Here, we report a facile strategy of wrapping perovskite grains within an oligomeric silica (OS) matrix in a core-shell geometry, which can synchronously passivate the defects at surfaces and grain boundaries and stabilize the grains at the nanoscale. We observe a significant reduction of trap density and elongation of carrier lifetime in OS-wrapped perovskites, which yields an increased efficiency of 21.5% for p-i-n structured PSCs with a decent open-circuit voltage of 1.15 V and a fill factor of 0.81. This all-around nanoscale grain wrapping leads to remarkable improvement of the operational stability of PSCs, sustaining 80% of the efficiency after "burn-in" under full sunlight with UV for more than 5200 h. Our findings provide a new pathway towards efficient and stable PSCs.