Traps for Electrons and Holes Limit the Efficiency and Durability of Polymer Light‐Emitting Electrochemical Cells

• DOI: 10.1002/adfm.202203643
• Publication Date: 2022-08-21T16:38:16Z
• Authors: Matthias Diethelm; Andrius Devižis; Wei‐Hsu Hu; Tao Zhang; Roman Furrer; Camilla Vael; Sandra Jenatsch; Frank Nüesch; Roland Hany
• Keywords: Ohmic contact; Diffusion capacitance

Abstract Polymer light‐emitting electrochemical cells (PLECs) and diodes (PLEDs) receive interest for large‐area lighting signage applications. During operation of a PLEC, p–i–n junction develops where electrons holes are injected into the film transported along n ‐ p ‐doped regions to intrinsic ( i ) region, they recombine under light emission. Conceptually, this resembles PLED device architecture equipped with Ohmic charge‐injection transport layers. The similarity between ‐region PLEC emissive layer is obvious; however, implication has not been examined in detail so far. For example, PLEDs it known that electron traps hinder transport, hole trap formation dictates long‐term durability. Here, PLECs electrical optical response driving breaks studied, current external irradiation probed, degradation followed absorption capacitance measurements. identified found limits lifetime, same manner as established PLEDs. It concluded charge semiconducting polymers present important, but far overlooked performance limitations PLECs.