Impact of Length of Branched Alkyl Side Chains on Thiazolothiazole-based Small Molecular Acceptors in Non-fullerene Polymer Solar Cells

Overview

Journal RSC Adv

Publisher Royal Society of Chemistry

Specialty Chemistry

Date 2024 Mar 11

PMID 38464695

Authors

Wenhong Peng

Jiyu Xiong

Tao Chen

Dong Zhao

Jinran Liu

Ning Zhang

Yefang Teng

Junting Yu

Weiguo Zhu

Affiliations

Soon will be listed here.

Abstract

It has been reported that the length of branched alkyl side chains on fused-ring electron acceptors confers different impacts on properties solubility of BJH blends. However, because this impact on a non-fused acceptor backbone has rarely been studied, we examined the impact of molecular optimization from alkyl chain tuning based on non-fused thiazolothiazole small-molecule acceptors. The length of the side chain on the thiophene bridge was modified from 2-butyloctyl to 2-ethylhexyl, which corresponds to small molecules TTz3(C4C6) and TTz3(C2C4), respectively. Compared with the reported TTz3(C6C8) with long alkyl side chains, TTz3(C4C6) and TTz3(C2C4) exhibited stronger molecular aggregation, higher absorption coefficients, and greater redshifted UV absorption. Unexpectedly, after the alkyl chain was slightly shortened in this type of acceptor system, devices were successfully fabricated, but it was necessary to reduce the blending concentration at low rotation speeds due to the sharp decrease in the solubility of corresponding acceptor materials. Thus, the obtained unfavorable thickness and morphology of the active layer caused a decrease in and FF. As a consequence, TTz3(C4C6)- and TTz3(C2C4)-based devices showed an unsatisfactory power conversion efficiency of 6.02% and 2.71%, respectively, when donors were paired with the wide bandgap donor J71, which is inferior to that of TTz3(C6C8)-based devices (8.76%). These results indicate that it is challenging to determine the limit of the adjustable range of side chains to modify non-fused thiazolothiazole small-molecule acceptors for high-performance non-fullerene solar cells.

References

Cui Y, Xu Y, Yao H, Bi P, Hong L, Zhang J . Single-Junction Organic Photovoltaic Cell with 19% Efficiency. Adv Mater. 2021; 33(41):e2102420. DOI: 10.1002/adma.202102420. View

Cui Y, Yao H, Zhang J, Xian K, Zhang T, Hong L . Single-Junction Organic Photovoltaic Cells with Approaching 18% Efficiency. Adv Mater. 2020; 32(19):e1908205. DOI: 10.1002/adma.201908205. View

Sun R, Wu Y, Yang X, Gao Y, Chen Z, Li K . Single-Junction Organic Solar Cells with 19.17% Efficiency Enabled by Introducing One Asymmetric Guest Acceptor. Adv Mater. 2022; 34(26):e2110147. DOI: 10.1002/adma.202110147. View

Cai Y, Li Y, Wang R, Wu H, Chen Z, Zhang J . A Well-Mixed Phase Formed by Two Compatible Non-Fullerene Acceptors Enables Ternary Organic Solar Cells with Efficiency over 18.6. Adv Mater. 2021; 33(33):e2101733. DOI: 10.1002/adma.202101733. View

Wang J, Zhan X . Fused-Ring Electron Acceptors for Photovoltaics and Beyond. Acc Chem Res. 2020; 54(1):132-143. DOI: 10.1021/acs.accounts.0c00575. View

Kim M, Ryu S, Park S, Pu Y, Park T . Designs and understanding of small molecule-based non-fullerene acceptors for realizing commercially viable organic photovoltaics. Chem Sci. 2021; 12(42):14004-14023. PMC: 8565376. DOI: 10.1039/d1sc03908c. View

Lin Y, Fan H, Li Y, Zhan X . Thiazole-based organic semiconductors for organic electronics. Adv Mater. 2012; 24(23):3087-106, 3081. DOI: 10.1002/adma.201200721. View

Guo C, Fu Y, Li D, Wang L, Zhou B, Chen C . A Polycrystalline Polymer Donor as Pre-Aggregate toward Ordered Molecular Aggregation for 19.3% Efficiency Binary Organic Solar Cells. Adv Mater. 2023; 35(41):e2304921. DOI: 10.1002/adma.202304921. View

Li S, Liu W, Li C, Shi M, Chen H . Efficient Organic Solar Cells with Non-Fullerene Acceptors. Small. 2017; 13(37). DOI: 10.1002/smll.201701120. View

10.

Wu J, Li G, Fang J, Guo X, Zhu L, Guo B . Random terpolymer based on thiophene-thiazolothiazole unit enabling efficient non-fullerene organic solar cells. Nat Commun. 2020; 11(1):4612. PMC: 7490407. DOI: 10.1038/s41467-020-18378-9. View

11.

Fan Q, Ma R, Yang J, Gao J, Bai H, Su W . Unidirectional Sidechain Engineering to Construct Dual-Asymmetric Acceptors for 19.23 % Efficiency Organic Solar Cells with Low Energy Loss and Efficient Charge Transfer. Angew Chem Int Ed Engl. 2023; 62(36):e202308307. DOI: 10.1002/anie.202308307. View

12.

Fan Q, Mendez-Romero U, Guo X, Wang E, Zhang M, Li Y . Fluorinated Photovoltaic Materials for High-Performance Organic Solar Cells. Chem Asian J. 2019; 14(18):3085-3095. DOI: 10.1002/asia.201900795. View

13.

Peng W, Zhang G, Zhu M, Xia H, Zhang Y, Tan H . Simple-Structured NIR-Absorbing Small-Molecule Acceptors with a Thiazolothiazole Core: Multiple Noncovalent Conformational Locks and D-A Effect for Efficient OSCs. ACS Appl Mater Interfaces. 2019; 11(51):48128-48133. DOI: 10.1021/acsami.9b16686. View

14.

Sugiyama F, Kleinschmidt A, Kayser L, Rodriquez D, Finn 3rd M, Alkhadra M . Effects of flexibility and branching of side chains on the mechanical properties of low-bandgap conjugated polymers. Polym Chem. 2019; 9(33):4354-4363. PMC: 6411084. DOI: 10.1039/C8PY00820E. View

15.

Guo B, Li W, Guo X, Meng X, Ma W, Zhang M . High Efficiency Nonfullerene Polymer Solar Cells with Thick Active Layer and Large Area. Adv Mater. 2017; 29(36). DOI: 10.1002/adma.201702291. View

16.

Chong K, Xu X, Meng H, Xue J, Yu L, Ma W . Realizing 19.05% Efficiency Polymer Solar Cells by Progressively Improving Charge Extraction and Suppressing Charge Recombination. Adv Mater. 2022; 34(13):e2109516. DOI: 10.1002/adma.202109516. View

17.

Liu Y, Zhang Z, Feng S, Li M, Wu L, Hou R . Exploiting Noncovalently Conformational Locking as a Design Strategy for High Performance Fused-Ring Electron Acceptor Used in Polymer Solar Cells. J Am Chem Soc. 2017; 139(9):3356-3359. DOI: 10.1021/jacs.7b00566. View

18.

Cao Z, Chen J, Liu S, Jiao X, Ma S, Zhao J . Synergistic Effects of Polymer Donor Backbone Fluorination and Nitrogenation Translate into Efficient Non-Fullerene Bulk-Heterojunction Polymer Solar Cells. ACS Appl Mater Interfaces. 2020; 12(8):9545-9554. DOI: 10.1021/acsami.9b22987. View