[12p-N322-1~18] 12.5 Organic solar cells

[12p-N322-10] Charge generation mechanisms in PM6/Y6 blend organic solar cells

〇Yasunari Tamai^1,2, Shin-ichiro Natsuda¹, Toshiharu Saito¹, Rei Shirouchi¹, Yuji Sakamoto¹, Hideo Ohkita¹ (1.Kyoto Univ., 2.JST PRESTO)

Keywords:transient absorption, charge separation, charge recombination

We examined the mechanisms underlying the generation of free charge carriers (FCs) in a state-of-the-art organic solar cell consisting of PM6 and Y6. We used transient absorption spectroscopy to track the time evolution of electroabsorption caused by electron–hole pairs generated at donor/acceptor interfaces. Selective excitation of Y6, which has a lower bandgap than PM6, resulted in slow yet efficient spatial charge dissociation without activation barrier on a time scale of 10 ps. We directly demonstrated that this slow yet efficient FC generation was driven by downhill energy relaxation through the energy cascade generated in the Y6 domain.