Highly efficient organic-inorganic hybrid perovskite quantum dot/nanocrystal light-emitting diodes using graphene electrode and modified PEDOT:PSS

Perovskite quantum dot (PQD)/nanocrystal (NC) light-emitting diodes (LEDs) have rapidly developed in last several years due to excellent optoelectronic properties of lead halide perovskites. However, the PDQ/NC LEDs using graphene electrodes haven't been reported despite of huge potential for applications in flexible displays and lighting sources. Herein, graphene is first used as electrodes of PQD and NC LEDs. To overcome film nonuniformity induced by graphene's hydrophobicity, a modification to poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with dimethyl sulfoxide (DMSO) and Triton X-100 codoping is reported, which effectively improves the wettability of graphene surface and sequent film quality. More importantly, the synergistic effect of DMSO and Triton X-100 alters the PEDOT:PSS morphology from a coiled structure to a nanofibril conductive network, sufficiently enhancing the electrical conductivity of PEDOT:PSS. With this modification strategy, two kinds of green LEDs with CH₃NH₃PbBr₃ PQD and FA_0.8Cs_0.2PbBr₃ (FA = CH(NH₂)₂) NC emission layer are successfully fabricated on the graphene anodes, with 4.4 and 7.4 fold enhancements on current efficiency compared to the counterpart without PEDOT:PSS modification, respectively. The film modification strategy and graphene-based PQD/NC LEDs in this work are expected to shed light on further design and manufacture of flexible highly efficient PQDs/NCs display and lighting devices.