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Elucidating the Role of Water‐Related Traps in the Operation of Polymer Field‐Effect Transistors
Author(s) -
Iqbal Hamna F.,
Waldrip Matthew,
Chen Hu,
McCulloch Iain,
Jurchescu Oana D.
Publication year - 2021
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.202100393
Subject(s) - materials science , transistor , polymer , dielectric , optoelectronics , passivation , semiconductor , organic semiconductor , trapping , water vapor , band gap , chemical physics , nanotechnology , voltage , electrical engineering , organic chemistry , composite material , chemistry , ecology , layer (electronics) , biology , engineering
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 Δ V th = −0.3 V and constant mobilities (<10% variation) after three months of storage, are fabricated.