Study of binary and ternary organic hybrid CdSe quantum dot photodetector

Abstract

The hybrid binary and ternary photodetectors (PDs) were fabricated from P3HT–PC₇₁BM with CdSe quantum dot (QD) materials. The absorption spectra of P3HT:PC₇₁BM (named as B1), P3HT:CdSe (B2) and P3HT:CdSe:PC₇₁BM (T) active blended material were analyzed in the wavelength range from 350 to 800 nm. The current density–voltage characteristics of the device were measured in dark and under illumination for study of detector detectivities and the contact with electrode. The ${J_{{\text{under}}\,{\text{illumination}}}}/{J_{\text{dark}}}$ ratio at −0.5 V for PDs B1, B2 and T is 1.1 × 10², 1.9 × 10² and 1.8 × 10³, respectively. The values of detectivity $({D^*})$ for B1, B2 and T are 1 × 10¹⁰, 2 × 10¹⁰ and 7 × 10¹¹ Jones, respectively. The ${D^*}$ for PD T is ten times in comparison with B1 and B2 PDs. The linear dynamic range (LDR) value for ternary device is more than double to both binary PDs. The absorption by CdSe QD increases the photon efficiency in the ternary detector, and at the same time the ternary detectors have high detectivity in broad spectral range. The responsivity of current to the light intensity exponent θ for detector B1, B2 and T is ~0.55, 0.55 and 0.62, respectively, which represents a complex process of electron hole generation, recombination and trapping within active material.