Efficient and stable inverted MA/Br-free 2D/3D perovskite solar cells enabled by α-to-δ phase transition inhibition and crystallization modulation

An FA-based organic derivative, namely BLSCl, has been explored as a spacer for MA/Br-free FA-based 2D/3D perovskites. A champion efficiency of 25.96% for the 0.1 cm 2 device and 24.54% (certified 23.94%) for the 1.01 cm 2 device have been achieved.