Medium Bandgap Nonfullerene Acceptor for Efficient Ternary Polymer Solar Cells with High Open-Circuit Voltage

Mukhamed L Keshtov; Alexei R Khokhlov; Dimitriy Y Shikin; Vladimir Alekseev; Giriraj Chayal; Hemraj Dahiya; Manish Kumar Singh; Fang Chung Chen; Ganesh D Sharma

doi:10.1021/acsomega.2c05141

Medium Bandgap Nonfullerene Acceptor for Efficient Ternary Polymer Solar Cells with High Open-Circuit Voltage

ACS Omega. 2023 Jan 2;8(2):1989-2000. doi: 10.1021/acsomega.2c05141. eCollection 2023 Jan 17.

Authors

Affiliations

¹ A.N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, Vavilova St., 28, Moscow 119991, Russian Federation.
² Inorganic and Analytical Chemistry Department, Tver State University, Sadovyi per. 35, Tver 170002, Russian Federation.
³ Department of Physics, Jai Narain Vyas University, New Campus, Jodhpur 342005, Rajasthan, India.
⁴ Department of Physics, The LNM Institute of Information Technology, Jamdoli, Jaipur 302031, Rajasthan, India.
⁵ Department of Photonics, National Yang Ming Chiao Tung University, Hsinchu 30010 Taiwan.
⁶ Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
⁷ Department of Electronics and Communication Engineering, The LNM Institute of Information Technology, Jamdoli, Jaipur 302031, Rajasthan, India.

Abstract

We have designed a new medium bandgap non-fullerene small-molecule acceptor consisting of an IDT donor core flanked with 2-(6-oxo-5,6-dihydro-4H-cyclopenta[c]-thiophene-4-ylidene) malononitrile (TC) acceptor terminal groups (IDT-TC) and compared its optical and electrochemical properties with the IDT-IC acceptor. IDT-TC showed an absorption profile from 300 to 760 nm, and it has an optical bandgap of 1.65 eV and HOMO and LUMO energy levels of -5.55 and -3.83 eV, respectively. In contrast to IDT-IC, IDT-TC has an upshifted LUMO energy level, which is advantageous for achieving high open-circuit voltage. Moreover, IDT-TC showed higher crystallinity and high electron mobility than IDT-IC. Using a wide bandgap D-A copolymer P as the donor, we compared the photovoltaic performance of IDT-TC, IDT-IC, and IDT-IC-Cl nonfullerene acceptors (NFAs). Polymer solar cells (PSCs) using P: IDT-TC, P: IDT-IC, and P:IDT-IC-Cl active layers achieved a power conversion efficiency (PCE) of 14.26, 11.56, and 13.34%, respectively. As the absorption profiles of IDT-IC-Cl and IDT-TC are complementary to each other, we have incorporated IDT-TC as the guest acceptor in the P: IDT-IC-Cl active layer to fabricate the ternary (P:IDT-TC: IDT-IC-Cl) PSC, demonstrating a PCE of 16.44%, which is significantly higher than that of the binary BHJ devices. The improvement in PCE for ternary PSCs is attributed to the efficient exploitation of excitons via energy transfer from IDT-TC to IDT-IC-Cl, suitable nanoscale phase separation, compact stacking distance, and more evenly distributed charge transport.