Europium (II)‐Doped All‐Inorganic CsPbBr3 Perovskite Solar Cells with Carbon Electrodes

All‐inorganic perovskite of CsPbBr3 thin‐films solar cells has attracted increasing interest in recent years due to its potential long‐term stability over the generally used hybrid perovskites. Herein, all‐inorganic CsPbBr3 perovskites are doped with Eu2+ to enhance the efficiency of perovskite solar cells (PVSCs). The perovskite films exhibit a better crystallinity with smooth morphology after the introduction of rare‐earth elements. Hence, the hole‐transport layer‐free device with presence of Eu2+ and low‐cost carbon electrode achieves both enhanced efficiency and stability. In particular, the power conversion efficiency (PCE) enhances from 5.66% to 7.28% with high VOC of 1.45 V by optimizing the doping concentration of Eu2+. In addition, the storage stability measurements reveal excellent performances of PCE without encapsulation in air with relative humidity of 70–80%. These results can pave changes in future inorganic PVSCs. All‐inorganic hole‐transport layer (HTL)‐free CsPbBr3‐based perovskite solar cells doped with Eu2+ are studied. The decrement in trap‐state density and suppression of nonradiative recombination after doping is achieved with a higher power conversion efficiency (PCE) of 7.28% and VOC of 1.45 V.