Nonexponetial relaxation of photoinduced conductance in organic field effect transistor

TL;DR

This study investigates the unusual slow relaxation of photoinduced charge carriers in organic transistors, proposing a hierarchical relaxation model influenced by gate voltage-dependent Coulomb interactions.

Contribution

It introduces a novel hierarchical relaxation model incorporating gate voltage effects to explain nonexponential charge relaxation in organic transistors.

Findings

Relaxation deviates from simple exponential decay.

Hierarchical models better fit the observed data.

Gate voltage influences charge trapping and relaxation dynamics.

Abstract

We report detailed studies of the slow relaxation of the photoinduced excess charge carriers in organic metal-insulator-semiconductor field effect transistors consisting of poly(3-hexylthiophene) as the active layer. The relaxation process cannot be physically explained by processes, which lead to a simple or a stretched-exponential decay behavior. Models based on serial relaxation dynamics due to a hierarchy of systems with increasing spatial separation of the photo-generated negative and positive charges are used to explain the results. In order to explain the observed trend, the model is further modified by introducing a gate voltage dependent coulombic distribution manifested by the trapped negative charge carriers.