Incorporation of Heteroatoms in Conjugated Polymers Backbone toward Air-Stable, High-Performance n-Channel Unencapsulated Polymer Transistors

Abstract

Organic field-effect transistors (OFETs) without any encapsulation of polymer semiconductor layers that still exhibit unipolar n-type characteristics under air conditions are very rare. In this study, we use fluorinated bithiophene as a donor, and bis(2oxoindolin-3-ylidene)-benzodifuran-dione (BIBDF, P1) and azasubstituted BIBDF (P2) as acceptor units to develop air-stable and unipolar electron transport polymer semiconductors. Unencapsulated OFETs based on P1 and P2 were fabricated and directly evaluated under air conditions. The highest effective mobility (μ e,max eff ) of 0.23 cm 2 V −1 s −1 was obtained for P2-based devices with high I on /I off ratio of >10 6 and low threshold voltage of 1.1 V. Moreover, P2 had high air stability and maintained unipolar electron transport with μ e,max eff of up 0.1 cm 2 V −1 s −1 and I on /I off ratio of >10 6 during the 60 days of air storage. The work provides an effective molecular design strategy to develop air-stable and high-performance n-channel unencapsulated polymer transistors that can be directly operated under air conditions.

Significant Difference in Semiconducting Properties of Isomeric All‐Acceptor Polymers Synthesized via Direct Arylation Polycondensation

“…[9,21] More importantly,the devices showed comparable performances even when measured in air (Figures 4c,d,g,h, Table 2). [22] The excellent air-stability of P2-based devices was most probably caused by the deep E LUMO of À4.00 eV. This result is remarkable,c onsidering that the organic layer was exposed to air in the case of the TC/BG device configurations and the air-stability of the n-type materials is generally poor.…”

“…[22] Choi et al proposed ameasurement reliability factor g to gauge the reliability of the reported values. [22] Choi et al proposed ameasurement reliability factor g to gauge the reliability of the reported values.…”

“…Thed evices were stored under ambient laboratory air conditions (R H = 40-60 %) and measured after 1, 2, and 4weeks in air ( Figure 5). [21,22] Thec urrently recognized benchmark material of n-type semiconducting polymers is P(NDI2OD-T2) with the E LUMO of À3.8 eV. Thed ecay of the electron mobilities may be caused by the diffusion of oxygen and moisture into the semi-conducting layers.…”

Core Fluorination Enhances Solubility and Ambient Stability of an IDT‐Based n‐Type Semiconductor in Transistor Devices

“…[ 21,22 ] The introduction of strongly electronegative fluorine groups has been shown to be an effective strategy for stabilizing the LUMO levels. [ 23–26 ] Owing to the small van der Waals radius, fluorination is highly attractive as these benefits can usually be achieved without disruption to backbone planarity from the introduction of undesired steric clashes. In addition, fluorination often helps to promote inter‐ and intramolecular interactions via a range of noncovalent interactions.…”

Synthesis and Nonlinear Optical Studies on Organic Compounds in Laser-Deposited Films

“…Many articles report the synthesis of the novel organic molecules or polymers with highly active chromophores and superior optical activity, as response to the demand of substances with NLO properties for various applications [83][84][85][86].…”