The Polymer Society of Korea

Abstract

Photomultiplication-type organic photodetectors (PM-type OPDs) have attracted attention due to their ultrasensitive detection capabilities attributed to high external quantum efficiency (EQE) and responsivity (R). However, novel polymer donors for PM-type OPDs have been rarely developed except for P3HT. In this study, we report benzobisoxazole-based polymer donors with π-spacers to investigate their effects on OPD performance. Compared to the control polymer without a π-spacer (PBB), both polymers with a π-spacer (PTBB) and an extended π-spacer (PUTTB) exhibited enhanced crystallinity. Notably, the extended π-spacer not only suppressed dark current density due to its alkyl chain but also increased the absorption coefficient, leading to superior specific detectivity (D^*). As a result, PUTTB-based devices achieved exceptional performance with EQE of 27,280%, R of 117 A/W, and D^* of 3.86 × 10¹³ Jones at a bias of -30 V.