An External Quantum Efficiency Model Toward Photoelectric Conversion Current of Organic Phototransistors

Abstract

Abstract Traditional external quantum efficiency (EQE) of organic phototransistors (OPTs) is defined as a ration of “the quantity of electrons (holes) devoting to output photocurrent” to “that of incident photons”, and is extensively used by researchers. Experiments show that the EQE values obtained thus are always much greater than 100%, surpass the limiting efficiency of photo-electrical conversion (PEC) in general circumstances, and thus can’t mirror the true PEC capacity and efficiency of OPTs. This is because there are the PEC and non-PEC currents in operating OPTs, and the non-PEC current arises from the non-PEC effects (e.g., injection barrier lowering, trap-assisted tunnelling, etc.) occurring in OPTs. In order to clarify the PEC process of OPTs and acquire the EQE value towards PEC current of OPTs, the PEC process of single organic layer OPTs is studied and an EQE model towards PEC current of them is built, and the EQE values of them are calculated by this model.