Optical Modeling-Assisted Characterization of Polymer:Fullerene Photodiodes

In this paper, the practical viability of an organic bulk heterojunction (BHJ)based photodiode is studied, including the analysis of dark current density (J_d in A/cm²), external quantum efficiency (EQE in percent), responsivity (R in A/W), noise-equivalent power (in W/Hz^1/2), and specific detectivity (Jones in cmHz^1/2/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 χ 10^-13, 1:13 χ 10^-13, and 1:94 χ 10^-14 A/Hz^1/2 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 χ 10¹¹, 5:93 χ 10¹¹, and 4:16 χ 10¹² Jones, respectively. The results demonstrated a performance of polymer:fullerence photodiode near equivalent to that of Si-based photodiodes.