Elucidating the Role of Water-Related Traps in the Operation of Polymer Field-Effect Transistors

Hamna F. Iqbal, Matthew Waldrip, Hu Chen, Iain McCulloch, Oana D. Jurchescu

Research output: Contribution to journalArticlepeer-review

Abstract

Conjugated polymers have gained momentum as serious contenders for next-generation flexible electronics, but their susceptibility to water represents a major problem. Atmospheric water is ubiquitous and its inadvertent diffusion into polymeric devices generates charge carrier traps, reducing their performance and stability. A good understanding of the physical processes associated with the presence of water is therefore necessary in order to be able to suppress the related trapping events and enable stable, high-performance devices. Here, evidence is shown that water introduces traps in the bandgap of organic semiconductors and the impact of these traps on the electrical properties of polymer organic field-effect transistors (OFETs) based on indacenodithiophene-co-benzothiadiazole (IDT-BT) is investigated. Monitoring device parameters and the trap density of states (t-DOS) during moisture extrication reveals the existence of two types of water-related traps: shallow traps originating from water inhabiting the voids of the polymer film and deeper traps arising from chemisorbed water present at the dielectric/polymer interface. A trap passivation method based on flame-annealing is introduced to eliminate the interfacial traps. As a result, stable OFETs, with threshold voltage shifts less than ΔVth = −0.3 V and constant mobilities (
Original languageEnglish (US)
Pages (from-to)2100393
JournalAdvanced Electronic Materials
DOIs
StatePublished - Jun 24 2021

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