Triphenylamine-based interlayer with carboxyl anchoring group for tuning of charge collection interface in stabilized p-i-n perovskite solar cells and modules

Interface engineering is one of the most critical directions in the development of photovoltaics (PVs) based on halide perovskites. A novel triphenylamine-based hole transport material (HTM) with a carboxyl anchoring group (TPATC) was developed for tuning the interface between nanocrystalline NiO and CsCH3(NH2)2PbI3-xClx absorber in p-i-n device architectures. Transient spectroscopy measurements revealed that modification of the NiO surface with TPATC in perovskite solar cells (PSCs) reduces the concentration of ionic defects by an order of magnitude and reconfigures the energy levels of traps. Interface engineering allowed to reach power conversion efficiency of 20.58% for small area devices (0.15 cm2) under standard AM 1.5 G conditions. Using TPATC interlayer also provided sustainability of the perovskite absorber to decomposition under operation conditions. After continuous light-soaking (ISOS-L-2 protocol), NiO/TPATC devices showed a slight decrease of 2% in maximum power. We explored the potential of TPATC to modify interfaces in perovskite solar modules (PSM, active area-64.8 cm2). By applying slot-die-coated TPATC, the PCE at AM 1.5 G conditions increased from 13.22% for NiO PSM to 15.64% for NiO/TPATC ones. This study provides new insights into the interface stabilization for perovskite solar cells, behavior of the ionic defects and their contribution to the long-term stability.