(8 mg/mL); Figure S2: the J-V curves recorded under forward scan of voltages from -0.1 to 1.5 V of the CsPbIBr2 PSCs without and with PEI modification (8 mg/mL); Figure S3: the statistics PCEs of 24 independent CsPbIBr2 PSCs fabricated without and with PEI modification (8 mg/...