Doping Effect of Ethylcarbazole-Contained-Silole in Blue-Sensitive Organic Photoconductive Device

Abstract

The photoconductive characteristics of the solution-processed organic device was improved by doping 1,1-dimethyl-2,5-bis(9-ethylcarbazol)-3,4-diphenylsilole (EtCz-silole) in poly(dioctylfluorenyl-co-benzo-thiadiazole) (F8BT). The maximum external quantum efficiency of 27% at −38 MV/m was achieved when the doping concentration of EtCz-silole was 40 wt%. This value was approximately 160 times higher than that of the reference device with F8BT only (0.17%). In addition, the signal-to-noise ratio (S/N), i.e., photocurrent density/dark current density was improved by doping EtCz-silole due to the increased photocurrent density and the reduced dark current density. The highest S/N of 1.4 × 10⁴ was observed by optimizing the concentration of EtCz-silole.

Keyword:

• organic photoconductive device
• color selectivity
• solution process
• fluorene polymer
• organic image sensor
• carrier delocalization
• silole derivative

Acknowledgment

This work was supported by JSPS KAKENHI (23750206).