Electronic correlations enhance optical absorption in graphene oxide-modified methylammonium lead iodide perovskite

We reveal unusual optical changes accompanied by spectral weight transfer analysis in methylammonium lead iodide (MAPbI3) as a function small fraction of graphene oxide (GO) concentrations using spectroscopic ellipsometry. Interestingly, we observe the tuneable optical properties of MAPbI3 due to the electronic correlation effect induced by GO using spectral weight transfer analysis. The increase of absorption in the MAPbI3 layer indicates a decrease in the number of holes due to the migration of these holes to the GO layer, suggesting the hole transport properties of GO. This work is the first to study the optical properties of GO combined with MAPbI3, which provides critical information that will be of great interest in the future development of high-performance PSCs, as well as how they reconcile several experimental studies that have demonstrated the positive impact of GO on charge extraction.