Interface charge transport of multilayer devices for exact analysis of charge behavior in organic optoelectronic devices

A unipolar charge device was utilized to gain information of the charge balance in organic optoelectronic devices to enhance efficiency and operational stability. Usually, a unipolar charge device is designed as a multilayer structure to improve charge transport and block injection of counter charges from electrodes. In this paper, the correlation between charge transport across the interlayer and corresponding bulk electrical parameters from quasi-static analysis was investigated. Although only the interlayer material was modified, the charge carrier mobility and drift charge carrier density of the light-emitting layer were totally changed, which originated from large series resistance due to charge accumulation at the interface. This result indicates that quantitative analysis of electrical properties from unipolar charge devices should be performed as background analysis to ensure efficient interface charge transport during operation.