Optical Modeling-Assisted Characterization of Polymer:Fullerene Photodiodes

Abstract

In this paper, the practical viability of an organic bulk heterojunction (BHJ)-based photodiode is studied, including the analysis of dark current density (Jd in A/cm2), external quantum efficiency (EQE in percent), responsivity (R in A/W), noise-equivalent power (in W/Hz1/2), and specific detectivity (Jones in cmHz1/2/W). The dark current was minimized down to 90 pA/cm2 in P3HT : PC60BM BHJ photodiodes by increasing the thickness, whereas the EQE maintained high values. The measured noise current was 2.20 × 10-13, 1.13 × 10-13, and 1.94 × 10-14 A/Hz1/2 for 45-, 55-, and 65-nm BHJ photodiodes, respectively. With those values, the calculated detectivity obtained, given light of a 550 nm wavelength, was 2.55 × 1011, 5.93 × 1011, and 4.16 × 1012 Jones, respectively. The results demonstrated a performance of polymer:fullerence photodiode near equivalent to that of Si-based photodiodes.