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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 31: Organic Electronics and Photovoltaics II
CPP 31.8: Talk
Wednesday, March 20, 2024, 17:00–17:15, H 0110
Loss mechanisms in low-bandgap organic solar cells — •Guorui He1, Atul Shukla1, Yonglin Cao2, 6, Yufei Gong3, Nurlan Tokmoldin2, Bowen Sun1, Drew Riley4, Mohammad Shadabroo2, Julian Steele5, Ardalan Armin4, Lei Meng3, Yongfang Li3, Safa Shoaee2, Dieter Neher1, and Felix Lang1 — 1Soft Matter Physics and Optoelectronics, University of Potsdam, Germany — 2Disordered Semiconductor Optoelectronics, University of Potsdam, Germany — 3Chinese Academy of Sciences, China — 4Swansea University, United Kingdom — 5The University of Queensland, Australia — 6South China University of Technology, China
We investigate and compare the loss mechanisms of low-bandgap OSCs based on the blend of the donor polymer PTB7-Th with two different NFAs BTPV-4F-eC9 and BTPV-4Cl-eC9, with a bandgap of 1.24 eV and 1.26 eV, respectively. Both NFAs exhibit the same conjugated core, except that in BTPV-4Cl-eC9, the four terminal fluorine atoms are replaced by four chlorines.
To understand how the change of the terminal groups is affecting the device performance, we investigate the various recombination processes of the two systems. The results show that the PTB7-Th:BTPV-4Cl-eC9 blend suffers from stronger bimolecular recombination and geminate recombination. In addition, EMPL reveals a significant voltage loss in both blends. Temperature-dependent SCLC measurements show a rather low electron mobility in PTB7-Th:BTPV-4Cl-eC9 system, which we relate to a larger disorder of the LUMO.
Keywords: organic solar cell; low bandgap; tandem solar cell; loss mechanisms; recombination processes