A Wide‐Bandgap Conjugated Polymer Based on Quinoxalino[6,5‐f  ]quinoxaline for Fullerene and Non‐Fullerene Polymer Solar Cells

Abstract

A wide‐bandgap conjugated polymer, PNQx‐2F2T, based on a ring‐fused unit of quinoxalino[6,5‐f ]quinoxaline (NQx), is synthesized for use as electron donor in polymer solar cells (PSCs). The polymer shows intense light absorption in the range from 300 to 740 nm and favorable energy levels of frontier molecular orbitals. The polymer has afforded decent device performance when blended with either fullerene‐based acceptor [6,6]‐phenyl‐C71‐butylric acid methyl ester ([70]PCBM) or non‐fullerene acceptor 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone‐methyl))‐5,5,11,11‐tetrakis(4‐n‐hexylphenyl)‐dithieno[2,3‐d: 2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (IT‐M). The highest PCEs of 7.9% and 7.5% have been achieved for [70]PCBM or IT‐M based PSCs, respectively. Moreover, the influence of molecular weight of PNQx‐2F2T on solar cell performance has been investigated. It is found that fullerene‐based devices prefer higher polymer molecular weight, while non‐fullerene devices are not susceptible to the molecular weight of PNQx‐2F2T. The device results are extensively explained by electrical and morphological characterizations. This work not only evidences the potential of NQx for constructing high‐performance photovoltaic polymers but also demonstrates a useful structure–performance relationship for efficiency enhancement of non‐fullerene PSCs via the development of new conjugated polymers.

Enhanced photothermal therapy performance of D–A conjugated polymers based on [1,2,3]triazolo[4,5-g]quinoxaline by manipulating molecular motion

“…This subtle discrepancy in the ε value and aggregation features could also be regarded as a result of the more planar molecular geometry and the larger degree of polymerization for polymer PCDT-QTz. 27,28 Negligible fluorescence signals were captured upon exciting the resulting polymers at their strongest absorbance peaks after many measurement attempts, even in different solvents (Fig. S4, ESI†), illustrating that nonradiative decay was the dominant pathway for excited-state deactivation.…”

Synergetic Effects of Random Copolymerization/Backbone Fluorination and Heterojunction of Terpolymer/g‐C3N4 Enhance Photocatalytic Hydrogen Evolution

“…The electronwithdrawing fluorine atoms on FTT units can induce F•••S noncovalent attractive interactions between the sulfur atoms, while DPP unit maintains the S⋯O noncovalent intramolecular conformational locks, which may play a key role in promoting backbone planarity and the charge mobility of conjugated polymers. [33][34][35][36][37] The chemical structure along with the possible noncovalent interactions and hydrogen bonding interactions of the terpolymers is displayed in Figure 1a. The photophysical, electrochemical, crystallinity, morphology, and photocatalystic hydrogen production properties of these terpolymers were optimized by varying the ratio of DPP and IID unit.…”

Quinoxaline‐Based D–A Copolymers for the Applications as Polymer Donor and Hole Transport Material in Polymer/Perovskite Solar Cells

“…In 2019, Huang and co‐workers also developed a NQx‐based D–A copolymer donor, PNQX‐2F2T (Figure 5), through copolymerizing difluoro‐substituted bithiophene (2F2T) D‐unit and NQx A‐unit. [ 86 ] The smaller size of the 2F2T unit without bulky chains allows for the closer alkyl‐alkyl interdigitation and more ordered interchain lamellar stacking for the polymer PNQX‐2F2T. In addition, the two F atoms on 2F2T unit can not only deepen the HOMO energy level of the polymer, but also enhance the noncovalent H···F and/or S···F interactions, which could lead to higher V oc of the corresponding device, and improve the backbone coplanarity and molecular crystallinity of the polymer.…”