Metal halide perovskites are an exciting emerging semiconductor technology which have been the subject of intense research efforts in the photovoltaic and optoelectronics research community for over a decade. As semiconductors, they are unusual due to their impressive defect tolerance, tunable bandgaps, and excellent optoelectronic properties. These properties have led to unprecedented developments in single junction photovoltaics where their power conversion efficiencies now rival those achievable with crystalline silicon. In addition to their successful demonstration in photovoltaics, perovskite semiconductors have shown great promise in photodetectors, transistors and as the emitting layer in light emitting diodes.  

Our understanding of the fundamental properties of these materials, and in particular their electronic structure in device architectures has been key to the continued developments in device performances. In this talk I will present our recent efforts to understand interfaces within perovskite photovoltaic and light emitting diode devices, focussing on understanding charge carrier dynamics and electronic structure within the perovskite itself and at the interfaces in our devices. I will discuss some of the difficulties faced when trying to study interfaces in these devices, and finally, I will discuss the operational stability of perovskite photovoltaics and share my opinion on how we can overcome the challenges we face in this area.