Organic-inorganic hybrid perovskite quantum dot light-emitting diodes using a graphene electrode and modified PEDOT:PSS

Perovskite quantum dot (PQD) light-emitting diodes (LEDs) have rapidly developed in the past several years due to the excellent optoelectronic properties of lead halide perovskites. However, PQD LEDs using graphene electrodes have not been reported despite their huge potential for applications in flexible displays and lighting sources. Herein, graphene was first used as the electrode of PQD LEDs. To overcome graphene's limitations such as hydrophobicity and graphene-induced film nonuniformity, the modification of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with Triton X-100 and dimethyl sulfoxide (DMSO) codoping was reported, which not only improved the wettability of the graphene surface and the sequent film quality, but also reduced the dissolution of the PQD solvent to the bottom poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine] and PEDOT:PSS. More importantly, the synergistic effect of Triton X-100 and DMSO altered 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, green PQD LEDs with CH₃NH₃PbBr₃ emission layers were successfully fabricated on graphene anodes, with 3.7- and 4.4-fold enhancements in luminance and current efficiency, respectively, compared to those of their counterparts without PEDOT:PSS modification. The film modification strategy and graphene-based PQD LEDs in this work are expected to shed light on the further design and manufacture of flexible highly efficient PQD display and lighting devices.