Type-I alignment in MAPbI₃ based solar devices with doped-silicon nanocrystals

In this work we couple silicon nanocrystals (Si NCs) with strong quantum confinement (< 4 nm diameter) with large grained MAPbI₃ films combining the perovskites excellent transport properties with the unique opto-electronic properties of quantum confined Si NCs. The electronic structures of MAPbI₃ and Si NCs, ideally aligned to form a type-I heterojunction, demonstrated improved carrier collection through a higher short-circuit current density (~ 20 mA cm⁻²) measured in photovoltaic test devices. The addition of p- and n-doped Si NCs within the MAPbI₃ films also showed unexpected and interesting device performance improvements, where the typical perovskite degradation process in ambient conditions was considerably slowed down and the overall device efficiency was observed to increase under light soaking. We attribute these improvements to the presence of Si NCs, which helped maintain the perovskite film qualities for more than 14 days in open atmosphere.