Issue 45, 2020

Efficient all-polymer solar cells based on a narrow-bandgap polymer acceptor

Abstract

The synthesis of novel polymer acceptors by polymerizing narrow-bandgap small molecule acceptors (SMAs) is an important strategy in the development of all-polymer solar cells (all-PSCs). Herein, a novel narrow-bandgap polymerized SMA (PSMA) PG1, based on a Y6-like building block of 2,2′-((2Z,2′Z)-((12,13-bis(2-butyloctyl)-3,9-dioctyl-12,13-dihydro-[1,2,5]thiadiazo-lo[3,4-e]thieno[2′′,3′′:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indo-le-2,10-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile copolymerized with a thienyl substituted benzo-[1,2-b:4,5-b′]dithiophene (BDT-T) unit, was designed and synthesized. The PSMA PG1 shows a broad and strong absorption in the region of 550–900 nm with a narrow optical bandgap (Eoptg) of 1.42 eV, a high maximum extinction coefficient of 1.19 × 105 cm−1 and a high electron mobility of 6.49 × 10−4 cm2 V−1 s−1, benefiting from the narrow bandgap, strong absorption and high electron mobility of the SMA building blocks. Furthermore, PG1 shows an expected up-shift in the lowest unoccupied molecular orbital energy level of −3.81 eV compared to the SMA building block, which is beneficial for achieving a higher open-circuit voltage (Voc) in all-PSCs. Upon processing with 1-chloronaphthalene (CN) as a solvent additive, the optimal all-PSC based on a blend of PBDB-T:PG1 achieved an outstanding PCE of 11.5% with a high Voc of 0.94 V, a short-circuit current density (Jsc) of 17.8 mA cm−2, a fill factor (FF) of 0.69 and a low energy loss of 0.48 eV. These Voc and PCE values are among the highest of the all-PSCs reported to date. These results indicate that PG1 is a promising polymer acceptor for highly efficient all-PSCs.

Graphical abstract: Efficient all-polymer solar cells based on a narrow-bandgap polymer acceptor

Supplementary files

Article information

Article type
Paper
Submitted
13 jul 2020
Accepted
12 okt 2020
First published
17 okt 2020

J. Mater. Chem. C, 2020,8, 16180-16187

Efficient all-polymer solar cells based on a narrow-bandgap polymer acceptor

Z. Yin, Y. Wang, Q. Guo, L. Zhu, H. Liu, J. Fang, X. Guo, F. Liu, Z. Tang, M. Zhang and Y. Li, J. Mater. Chem. C, 2020, 8, 16180 DOI: 10.1039/D0TC03303K

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