From Unipolar, WORM‐Type to Ambipolar, Bistable Organic Electret Memory Device by Controlling Minority Lateral Transport

Abstract Write‐once‐read‐many (WORM) memory behavior is often observed in polymer electret memory (PEM) devices, greatly limiting their overall performance. This paper systematically investigates the device physics of PEM devices with poly(α‐methylstyrene) as a charge trapping layer and pentacene as a semiconductor channel. The combined experiments on transistors, capacitances, and optical spectroscopy reveal that both the WORM memory behavior after negative and positive pulses and the gradual formation of memory after the continuous scanning are the results of the deficiency in minority (electrons) transport and trapping. Corresponding quantitative models are established and well explain the two‐stage, gradual trapping processes to form memory. By reducing the structural disorder and lateral channel length, ambipolar, bistable memory and much faster formation of memory window is obtained based on the same PEM device. The insights into device physics of PEM devices are expected to facilitate the design of organic, nonvolatile memory devices with high programming and erasing efficiencies.