Side‐chain engineering of regioregular copolymers for high‐performance polymer solar cells processed with nonhalogenated solvents

Abstract

Conjugated polymers for bulk heterojunction polymer solar cells (BHJ PSCs) should be processed with nonhalogenated solvents because of environmental concerns. Here, we report novel regioregular copolymers for high-performance PSCs processed with nonhalogenated solvents. The regioregular copolymers (i.e., rr-PfBT2f4T-2OD and rr-PfBT2f4T-2DT) consist of 3 00 ,4 0 -difluoro-2,2 0 :5 0 ,2 00 :5 00 ,2 000 -quaterthiophene (2f4T) with different side chains (2-octadodecyl (OD) and 2-decyltetradecyl (DT)) and 5-fluorobenzo[c][1,2,5]thiadiazole (fBT). The regioregular copolymers with controlled fBT orientation show high solubility in nonhalogenated solvents. Both regioregular copolymers possess suitable energy levels, leading to sufficient energy offsets with a nonfullerene acceptor, BTP-eC11. An rr-PfBT2f4T-2DT:BTP-eC11-blended film exhibited predominant face-on orientation compared to the rr-PfBT2f4T-2OD:BTP-eC11-blended film. In addition, the rr-PfBT2f4T-2DT:BTP-eC11-blended film showed much more balanced hole/electron mobility (μ h /μ e $ 4.73) than rr-PfBT2f4T-2OD: BTP-eC11-blended film (μ h /μ e $ 45.86). Therefore, rr-PfBT2f4T-2DT:BTP-eC11-based PSCs, processed with 1,2,4-trimethylbenzene, showed a power conversion efficiency of 13.21% which is 60% higher than rr-PfBT2f4T-2OD: BTP-eC11-based PSCs.

Molecular structural descriptor‐assisted machine learning for organic photovoltaics with perylenediimide acceptors

“…When two PDI monomers were directly connected without a linker structural unit in the molecular structure, zero was assigned to the position corresponding to the linker unit in the descriptor. Following the descriptor generation principle, the example Ph1 is described by (1,3,14), as shown in Figure 2. Finally, we created an encoder that defines a binary OPV as a matrix consisting of five numbers: one integer representing the index of a polymer donor, three integers representing the descriptor of a PDI-based acceptor, and one decimal number representing the D:A mass fraction.…”

“…In addition to the development of the process for BHJ morphological optimization, the series of steps for synthesizing new materials, testing numerous material combinations, and fine-tuning the chemical composition ratios require numerous trials and errors. [9][10][11][12][13][14] Therefore, machine learning (ML) approaches to screen numerous BHJ combinations in a short time and with little effort, based on a comprehensive understanding of the potential of OPV materials, have attracted considerable attention. 15,16 State-of-the-art OPV ML models achieved superior accuracy with a variety of input data types and algorithms.…”

Recent progress on radiofluorination using metals: strategies for generation of C–18F bonds

“…Carbon-fluorine bond formation is an important research topic in organic synthesis because of the widespread applications of organofluorine compounds in pharmaceuticals, agricultural applications, and materials science. [1][2][3][4][5][6][7] The insertion of a fluorine atom in a drug molecule can alter its physical, chemical, and biological properties. Furthermore, these alterations can also importantly affect drug metabolism and pharmacokinetics.…”

Achieving an excellent efficiency of 11.57% in a polymer solar cell submodule with a 55 cm2 active area using 1D/2A terpolymers and environmentally friendly nonhalogenated solvents

“…These solvents are employed to ensure sufficient solubility and favorable molecular ordering. Unfortunately, the use of these halogenated solvents is limited in mass production because of environmental toxicity concerns 20‐27 . Furthermore, due to the strong temperature dependent aggregation (TDA) property of the PM6 polymer, PM6‐based large‐area PSCs fabricated using large‐scale coating methods exhibit a significant reduction in PCE.…”

“…Unfortunately, the use of these halogenated solvents is limited in mass production because of environmental toxicity concerns. [20][21][22][23][24][25][26][27] Furthermore, due to the strong temperature dependent aggregation (TDA) property of the PM6 polymer, PM6-based large-area PSCs fabricated using large-scale coating methods exhibit a significant reduction in PCE. For example, PM6-based small-area (0.12 cm 2 ) PSCs exhibit a PCE of 15.1%.…”