Highly\nEfficient Polymer-Based Optoelectronic Devices Using PEDOT:PSS and\na GO Composite Layer as a Hole Transport Layer

Abstract

We\ndemonstrate highly efficient polymer light-emitting diodes (PLEDs),\nas well as polymer solar cells (PSCs), using a solution-processable\npoly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS):graphene\noxide (GO) (PEDOT:GO) composite layer as hole transport layers (HTLs).\nThe PEDOT:GO composite HTL layer shows enhanced charge carrier transport\ndue to improved conductivity by benzoid–quinoid transitions\nwith a well-matched work function between GO (4.89 eV) and PEDOT:PSS\n(4.95 eV). Moreover, it reduces remarkably exciton quenching and suppresses\nrecombinations that bring higher charge extraction in PSCs and increases\nthe recombinations of holes and electrons within the active layer\nby the blocking behavior of the electrons from a fluorescent semiconductor\ndue to the existence of GO with large bandgap (∼3.6 eV) in\nthe PEDOT:GO composite layer, therefore leading to an enhancement\nof device efficiency in PLEDs and PSCs. The optimized PLEDs and PSCs\nwith a PEDOT:GO composite HTL layer shows the maximum luminous efficiency\nof 21.74 cd/A (at 6.4 V) for PLEDs, as well as the power conversion\nefficiency of 8.21% for PSCs, which were improved by ∼220 and\n12%, respectively, compared to reference PLEDs and PSCs with a PEDOT:PSS\nlayer.