[18p-G202-1~9] 12.5 Organic solar cells

[18p-G202-8] Light-Induced ESR Spectroscopy of Charge-Accumulation States in PNTz4T Polymer Solar Cells

〇Shinpei Kamiya¹, Takahiro Watanabe¹, Masahiko Saito², Itaru Osaka², Kazuhiro Marumoto^1,3 (1.Tsukuba Univ., 2.Hiroshima Univ., 3.TREMS, Univ. of Tsukuba)

Keywords:organic solar cell, ESR, degradation mechanism

We report electron spin resonance (ESR) spectroscopy of high-efficiency organic thin-film solar cells with a p-type semiconducting polymer PNTz4T to investigate the intrinsic deterioration mechanism during device operation from a microscopic viewpoint. The observed light-induced ESR signals consisted of two components. Using the ESR analyses of the samples (ITO/ZnO and ZnO/PNTz4T:PC₆₁BM), the narrow and broad components are ascribed to electrons and holes trapped in ZnO, respectively. The number of spins of the broad component gradually increased and the short-circuit current density (J_sc) concomitantly decreased during device operation. Thus, we demonstrate their correlation and find that the broad component is the factor for the intrinsic internal deterioration of the device performance.