Parts | Days | Selection | Search | Updates | Downloads | Help

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 Cao^{2, 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