Mesoporous-Carbon-Based Fully-Printable All-Inorganic Monoclinic CsPbBr3 Perovskite Solar Cells with Ultrastability under High Temperature and High Humidity

The all-inorganic CsPb(IxBr1–x)3 (0 ≤ x ≤ 1) perovskite solar cells (PSCs) are attractive by virtue of their high environmental and thermal stability. Nevertheless, multiple-step deposition and high annealing temperature (>250 °C) and the structural and optoelectronic properties changes upon temperature-dependent phase-transition are potential impediments for highly efficient and stable PSCs. Herein, a space-confined method to fabricate stable lower-order symmetric pure monoclinic CsPbBr3 phase at low temperature (<50 °C) is for the first time reported. It is found that the carbon-based mesoporous fully printable area can inhibit the phase transition to get a pure phase. Therefore, the device exhibits a power conversion efficiency of 7.52% with a low hysteresis index of 0.024. Moreover, the device passed the 1000 h 85 °C thermal test and the 200 cycles thermal cycling test according to IEC-61625 stability tests. These are critical progresses for achieving long-term stability and the stable pure inorganic perovskite phase of high-performance photovoltaics.