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/cm
²
), 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/cm
²
in P3HT : PC
₆₀
BM 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 10
¹¹
, 5:93 χ 10
¹¹
, and 4:16 χ 10
¹²
Jones, respectively. The results demonstrated a performance of polymer:fullerence photodiode near equivalent to that of Si-based photodiodes.