Effect of complexing agent concentration on photovoltaic performance of TiO2@MAPbI3 core-shell structured nanowire arrays

In TiO₂@MAPbI₃ core-shell nanowire array solar cells, the full use of incident light, rapid transportation of carrier, and enhancement of mutual properties are realized as a whole. However, the perovskite layer is prone to defects during the growth process, and the density of deep energy level defects on the surface of polycrystalline perovskite layers is 1–2 orders of magnitude higher than that of the bulk phase, so the surface composite mainly limits the carrier lifetime of perovskite layers. To address the interfacial defects of perovskite layers, it has been shown that modification of the ETL surface using complexing agents can eliminate or improve these defects by forming ionic and coordination bonds with the perovskite surface. However, the number of ligands and the number of unliganded ions will directly affect the degree of improvement of the hybridized perovskite defects. So we investigated the effect of complexing agent concentration on the photovoltaic performance of NWs array solar cells, and when TiO₂ NWss were modified by complexing agent at a concentration of 0.3 mol/L the best performance of the devices was achieved with a PCE of 9.86 % and an increase of 37.1 %. It shows that the concentration of the complexing agent has a significant impact on the carrier transport characteristics and photovoltaic performance of the core-shell structure NWs array. This will provide some guidances for improving the photovoltaic performance of core-shell NWs array solar cells.