High-efficiency perovskite solar cell based on TiO2 nanorod arrays under natural ambient conditions: Solvent effect

Well oriented TiO2 nanorod arrays (TNRAs), served as an electron transmission carrier, have become the hotspot in perovskite solar cells (PSCs) for providing the direct channel for efficient charge transport and facilitating the pore filling of perovskite. However, the interfacial contact between perovskite film and TNRAs is one of the main factors that restricts the power conversion efficiency (PCE) of TNRAs based PSCs at present. In this paper, by employing a two-step spin-coating method, the influence of PbI2 solvent such as PbI2/DMSO + ACN and PbI2/DMSO + DMF + HAc solutions, on the preparation and performance of TNRAs based PSCs was intensively investigated. More importantly, the relationship between the micro-characteristics of perovskite film, especially the interfacial contact between perovskite film and TNRAs, and macro-properties of PSCs was elucidated. Experimental results indicate that two compact perovskite films with similar large grain size were synthesized on TNRAs from the two different PbI2 solvents, which leads to similar short circuit current densities (J(sc)). However, the PSC from PbI2/DMSO + DMF + HAc solution shows a larger V-oc of 1.10 V compared with that from PbI2/DMSO + ACN solution, and thus a higher PCE of 16.57% was achieved under natural ambient conditions. The key reasons for the enhanced performance may be ascribed to the faster electron extraction and larger electron recombination resistance in the PSC, which mainly depends on the nature of perovskite/TNRAs interfaces.