Role of graphene ordered modifiers in regulating the organic halide perovskite devices

Abstract The three reduced graphene oxide (rGO)-based precursors subsuming pristine rGO, rGO-g-poly(3-hexylthiophene) (P3HT), and rGO-g-poly(3-thiophene ethanol) (PTEt) were utilized to manipulate the optical, morphological, and electrical properties of perovskite solar cells. Via incorporation of rGO nanosheets, all device characteristics plummeted (13.65 mA/cm2, 63%, and 0.93 V) and the power conversion efficiency (PCE) dropped to 8.00% (from 11.10%), indicating that the bared rGO precursors were not capable of modifying the active layer. The grafting of rGO surface with polymeric backbones effectively improved the cell parameters via enabling the rGO nanosheets to control the morphology, ordering, and absorbance. In particular, the self-designed grafts such as regioregular P3HT chains further improved the morphological and photovoltaic characteristics. The P3HT-grafted rGO precursors resulted in a PCE of 15.15% (22.15 mA/cm2, 72%, 0.95 V), which was higher than efficiency (= 13.91%) recorded in CH3NH3PbI3 + rGO-g-PTEt systems (20.63 mA/cm2, 71%, 0.95 V), thanks to more intensified crystalline peaks, higher absorbance, larger grain sizes (averaged in 570 nm and peaked in 750 nm) and lower charge-transfer resistance (93.2 versus 109.4 Ω). As a fingerprint of high reproducibility, the distributions of photovoltaic features were also the narrowest in the rGO-g-P3HT based perovskite solar cells.