Mixed solvents for the optimization of morphology in solution-processed, inverted-type perovskite/fullerene hybrid solar cells

We investigate mixed solvents of N,N-dimethylformamide (DMF) and gamma-butyrolactone (GBL) to produce the smooth surface of a perovskite film and uniform crystal domains. This ideal morphology from mixed solvents enhances the power conversion efficiency to over 6% by improving the exciton dissociation efficiency and reducing the recombination loss at both interfaces of PEDOT:PSS/perovskite and perovskite/PCBM.