Constructive effects of the interfacial properties: A strategy to design hole transport materials for high performance perovskite solar cells

Properties of three organic hole transport materials (HTMs), FDT, PEH-2, and SNE (See Scheme 1) are investigated by combination of molecular dynamics and first principle calculations. Besides the isolated molecules, the interfacial properties of HTMs adsorbed on CH3NH3PbI3 (110) surface are firstly theoretically investigated in detail to evaluate the HTM performance. The overall performance of isolated HTMs is evaluated in terms of frontier molecular orbital, absorption spectrum, and hole mobility. After HTMs are adsorbed on CH3NH3PbI3 (110) surface, the significantly reduced band gap of SNE can improve the light harvesting ability of perovskite solar cells (PSCs). Moreover, the energy difference between HOMO energy level of HTM and valence band of CH3NH3PbI3 (110) surface for SNE is the smallest in three studied molecules indicating the largest V-oc of PSCs. Although HTM-CH3NH3PbI3 system is closer to the real environment than isolated HTMs, the adsorbed HTM-CH3NH3PbI3 is rarely considered because of its expensive computational cost and structural complexity. We expected that this work would be helpful to deeply understand the property of HTMs applied in PSCs.