Realizing n-Type Field-Effect Performance via Introducing Trifluoromethyl Groups into the Donor–Acceptor Copolymer Backbone

Abstract

Developing a new strategy to obtain n-type organic semiconductors is crucial for the advance of organic electronics. We herein report the synthesis and investigation of a series of donor–acceptor-type diazaisoindigo-based copolymers, named PAIID-TFBVB-C1, PAIID-TFBVB-C3, and PAIID-BVB-C3. After introduction of the trifluoromethyl groups with strong electron-withdrawing ability into the molecular backbone of PAIID-BVB-C3-containing stilbene units, the obtained polymer PAIID-TFBVB-C3 shows obvious blue-shifted UV–vis absorption profiles because of the enlarged band gap revealed by the theoretical simulation. Meanwhile, both the energy levels of the lowest unoccupied molecular orbital (LUMO) of PAIID-TFBVB-C1 and PAIID-TFBVB-C3 with trifluoromethyl groups are lower than that of PAIID-BVB-C3 without trifluoromethyl groups, reducing the energy difference between the LUMO energy level and the work function of the source-drain electrode and further facilitating electron injection. Consequently, both the PAIID-TFBVB-C1- and PAIID-TFBVB-C3-based devices show typical n-type field-effect performance with electron mobilities of 0.11 and 0.04 cm2 V–1 s–1, respectively, whereas devices based on PAIID-BVB-C3 exhibit p-type semiconducting performance with a hole mobility of 0.14 cm2 V–1 s–1. Our results demonstrate that it is a feasible strategy to acquire n-type semiconducting materials by introducing the electron-withdrawing trifluoromethyl groups into the polymer backbone.

Nonchlorinated Solubility Enhanced by Lipophilicity: An Effective Strategy for Environmentally Benign Processing of Rigidly Regular n‐type Polymeric Semiconductors

“…In this article we will illustrate the positive correlation between lipophilicity and solubility through incorporating non-twisted backbone. On the other hand, their strong electron-withdrawing property could efficiently reduce the HOMO levels, [14] which had been reported formerly in OFETs [15] and OPVs. [16] It was reasonable that the incorporation of CF 3 and SCF 3 to the (E)-1,2-di(thiophen-2-yl) ethane (TVT) could realize both considerably high solubility and weak-donor property (Figure 1c).…”

Semiconducting Polymers Based on Isoindigo and Its Derivatives: Synthetic Tactics, Structural Modifications, and Applications

“…[ 24 ] Based on M4 , many polymers with different donor moieties have been synthesized and exhibited excellent OFET performance, such as P17 and P18 . [ 24,94–96 ] Interestingly, the charge transport properties of these polymers to some extent depend on device structure. For example, P17 showed ambipolar transport with hole and electron mobilities of 2.33 and 0.78 cm 2 V −1 s −1 , respectively, in top‐gate bottom‐contact (TGBC) devices, and showed unipolar hole transport with mobility of 7.28 cm 2 V −1 s −1 in bottom‐gate bottom‐contact (BGBC) devices.…”

Acceptor Modulation Strategies for Improving the Electron Transport in High‐Performance Organic Field‐Effect Transistors

“…Donors (D): Benzene (Ph), [32,33] thiophene (T), [34] selenophene (Se), [35] dithiophene (TT), [36,37] bithiophene (2T), [38] benzodithiophene (BDT), [39,40] thiophene-vinyl-thiophene (TVT), [41] benzene-vinyl-benzene (BVB), [42] etc.…”

“…Two copolymers (P33a and P33b) of AIID and BVB or TFBVB were synthesized. [ 42 ] Due to the introduction of CF 3 groups, the LUMO energy level of P33b was −3.69 eV, which was 0.22 eV lower than that of P33a. GIXRD results indicated that the π–π stacking distance of P33b (3.53 Å) was larger than that of P33a.…”