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Item type:Publication, Field effect passivation in perovskite solar cells by a LiF interlayer(John Wiley and Sons Inc, 2022-08-01)The fullerene C 60 is commonly applied as the electron transport layer in high‐efficiency metal halide perovskite solar cells and has been found to limit their open circuit voltage. Through ultra‐sensitive near‐UV photoelectron spectroscopy in constant final state mode (CFSYS), with an unusually high probing depth of 5–10 nm, the perovskite/C 60 interface energetics and defect formation is investigated. It is demonstrated how to consistently determine the energy level alignment by CFSYS and avoid misinterpretations by accounting for the measurement‐induced surface photovoltage in photoactive layer stacks. The energetic offset between the perovskite valence band maximum and the C 60 HOMO‐edge is directly determined to be 0.55 eV. Furthermore, the voltage enhancement upon the incorporation of a LiF interlayer at the interface can be attributed to originate from a mild dipole effect and probably the presence of fixed charges, both reducing the hole concentration in the vicinity of the perovskite/C 60 interface. This yields a field effect passivation, which overcompensates the observed enhanced defect density in the first monolayers of C 60 . - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Hydrogen effects at sputtered Tb-doped AlNxOy:H / c-Si(p) interfaces: A transient surface photovoltage spectroscopy study(Elsevier B.V., 2022-10-01)In the present work, we studied the interface of terbium doped aluminum oxynitride (Tb-doped AlNxOy:H) deposited under different hydrogen flows with p-type doped crystalline silicon by applying transient surface photovoltage spectroscopy. We observed strong accumulation with concomitant passivation of boron acceptors in the crystalline silicon and defect generation near the interface. With increasing hydrogen flows, the net negative charge in the Tb-doped AlNxOy:H layer decreased, surface photovoltage signals related to defects increased, surface photovoltage transients decayed faster, and the slowest relaxation of charge carriers separated in space changed from trap limited to hopping transport via an exponential distribution of trap states in energy.