Abstract
Perovskite absorbers have witnessed a remarkable efficiency increase in last couple of years. To meet the commercialization challenge, reduced cost and improved efficiency are the two critical factors. We report on a hole transport layer free device synthesized under ambient air conditions of high humidity of 50% using TiO
2
-graphene oxide nanocomposite as electron selective contact. The devices achieved a power conversion efficiency of 5.9%. We introduce a novel synthesis route for TiO
2
-graphene oxide (GO) composite allowing superior charge transport properties. Incorporation of GO in TiO
2
allows achieving higher power conversion efficiencies while working under ambient air conditions. Ambient air synthesis with hole transport free architecture has the potential to reduce the cost of this technology leading to commercial viability.