Highly Efficient Phenoxazine Core Unit Based Hole Transport Materials for Hysteresis-Free Perovskite Solar Cells

Two novel simple-constructed and low-cost hole transport materials (HTMs) POZ9 and POZ10, incorporating a phenoxazine (POZ) core unit, were designed and synthesized for application in perovskite solar cells (PSCs). The typically semblable molecular structure of POZ9 and POZ10 cause them to possess similar energy levels. However, their photovoltaic performances are quite different from each other because of the small variations of N-substitution on POZ ring. The PSCs based on POZ10, which contains three N,N-di-4-methoxyphenylamino units, achieved a power conversion efficiency (PCE) of 19.4%, while the PSC adopting POZ9 as HTM obtained a lower PCE of 17.1%. Moreover, the light intensity dependence research showed that POZ10 has a better hole transporting ability and can efficiently resist the charge recombination.