High Efficiency Polymer Solar Cells with Efficient Hole Transfer at Zero Highest Occupied Molecular Orbital Offset between Methylated Polymer Donor and Brominated Acceptor

Chenkai Sun; Shucheng Qin; Rui Wang; Shanshan Chen; Fei Pan; Beibei Qiu; Ziya Shang; Lei Meng; Chunfeng Zhang; Min Xiao; Changduk Yang; Yongfang Li

doi:10.1021/jacs.9b09939

High Efficiency Polymer Solar Cells with Efficient Hole Transfer at Zero Highest Occupied Molecular Orbital Offset between Methylated Polymer Donor and Brominated Acceptor

J Am Chem Soc. 2020 Jan 22;142(3):1465-1474. doi: 10.1021/jacs.9b09939. Epub 2020 Jan 14.

Authors

Chenkai Sun^{1

2}, Shucheng Qin^{1

2}, Rui Wang³, Shanshan Chen^{4

5}, Fei Pan^{1

2}, Beibei Qiu^{1

2}, Ziya Shang^{1

2}, Lei Meng¹, Chunfeng Zhang³, Min Xiao³, Changduk Yang⁵, Yongfang Li^{1

2

6}

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China.
² School of Chemical Science , University of Chinese Academy of Sciences , Beijing 100049 , China.
³ National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China.
⁴ MOE Key Laboratory of Low-grade Energy Utilization Technologies and Systems, CQU-NUS Renewable Energy Materials & Devices Joint Laboratory, School of Energy & Power Engineering , Chongqing University , Chongqing 400044 , China.
⁵ Department of Energy Engineering, School of Energy and Chemical Engineering, Low Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798 , Republic of Korea.
⁶ Laboratory of Advanced Optoelectronic Materials, College of Chemistry, Chemical Engineering and Materials Science , Soochow University , Suzhou , Jiangsu 215123 , China.

PMID: 31904234
DOI: 10.1021/jacs.9b09939

Abstract

Achieving efficient charge transfer at small frontier molecular orbital offsets between donor and acceptor is crucial for high performance polymer solar cells (PSCs). Here we synthesize a new wide band gap polymer donor, PTQ11, and a new low band gap acceptor, TPT10, and report a high power conversion efficiency (PCE) PSC (PCE = 16.32%) based on PTQ11-TPT10 with zero HOMO (the highest occupied molecular orbital) offset (ΔE_HOMO(D-A)). TPT10 is a derivative of Y6 with monobromine instead of bifluorine substitution, and possesses upshifted lowest unoccupied molecular orbital energy level (E_LUMO) of -3.99 eV and E_HOMO of -5.52 eV than Y6. PTQ11 is a derivative of low cost polymer donor PTQ10 with methyl substituent on its quinoxaline unit and shows upshifted E_HOMO of -5.52 eV, stronger molecular crystallization, and better hole transport capability in comparison with PTQ10. The PSC based on PTQ11-TPT10 shows highly efficient exciton dissociation and hole transfer, so that it demonstrates a high PCE of 16.32% with a higher V_oc of 0.88 V, a large J_sc of 24.79 mA cm^-2, and a high FF of 74.8%, despite the zero ΔE_HOMO(D-A) value between donor PTQ11 and acceptor TPT10. The PCE of 16.32% is one of the highest efficiencies in the PSCs. The results prove the feasibility of efficient hole transfer and high efficiency for the PSCs with zero ΔE_HOMO(D-A), which is highly valuable for understanding the charge transfer process and achieving high PCE of PSCs.