Angle-resolved photoemission of CsPbBr3

Metal halide perovskites are transforming photovoltaics, lighting, and many other optoelectronic applications, yet there is no agreement on the reason for their remarkable efficiency. For the example of CsPbBr3, we study the temperature dependent electronic structure by angle-resolved photoemission. Based on our results, we explain the formation of the fundamental gap, the light effective mass, and the long lifetime. We support this by tight-binding calculations and x-ray-diffraction-based band structure calculations including octahedral tilting and rotation. We show that this also affects the surface electronic structure. Our reassessment also includes the assumed surface termination.