Enhanced Performance Organic Light Emitting Diode With CuI:CuPC Composite Hole Transport Layer

Abstract

Composite materials have attracted significant attention owing to their effective application in producing high-efficiency organic light emitting diodes (OLEDs). Hole transport layers are important and play a noteworthy character in improving the efficiency and stability of OLED. In this work, we have investigated the doping effect of the copper iodide (CuI) into copper (II) phthalocyanine (CuPC) hole transport layer on the performance of OLED. The composite hole transport layer was employed in solution processed OLED consisting 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl (CBP) as a host, Tris (2-phenylpyridine) iridium (III) (Ir(ppy)3) as dopant, 2,2',2-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) as electron transport layer, lithium fluoride as electron injection layer, and aluminum as cathode. We perceived that doping of CuI into CuPC led to a higher performance enhancement for the OLED than the use of PEDOT:PSS as hole transport layer. The OLED reveals maximum power efficiency (PE), current efficiency (CE) and external quantum efficiency (EQE) 74.1 lmW−1, 70 cdA−1 and 18.5%, respectively, with doping 20 wt % CuI into CuPC, while PEDOT:PSS based OLED exhibits PE of 48 lmW−1, CE of 49 cdA−1 and EQE of 14%. The enhancement of PE, CE and EQE of 33.3, 34.6 and 32%, which may be attributed to the optimized doping ratio of the CuPC and the CuI showing improved hole transport ability, optical properties, surface roughness, and the reduced hole injection barrier. Our outcomes deliver an efficient tactic to replace PEDOT:PSS and enhance the performance of OLED by incorporating CuI as dopants into CuPC.