Dual donor bulk-heterojunction to realize a quick and more sensitive organic visible photodector

Abstract

We present herein, an interpenetrating organic dual donor bulk-heterojunction platform for promising visible light sensing utility. The photoactive layer of the sensor is comprised of ternary organic blend of 7,16-bis(3,3-dimethyl-3H-indol-2-yl)-5,14-dihydrodibenzo [b,i][1,4,8,11] tetraazacy clotetradecine (LH2), poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PC61BM). Dual donor (LH2 and P3HT) configuration has been utilized for spectral enhancement in visible range. The role of LH2 doping in the P3HT:PC61BM binary blend in the present sensor has been justified by the improved light absorption in the short wavelength range. The photoluminescence (PL) spectra of the LH2: P3HT binary blend has been studied to optimize the volumetric ratio of the donor moieties for improved charge transfer efficiency in the ternary blend. The photo detector’s electrical parameters have been recorded under varied illumination intensities. The current density-voltage (J–V) characteristics of the fabricated sensors exhibit a strong relationship with incident optical power densities. The sensor has revealed high photoconductive sensitivity ~ 5.33 × 10− 11 (S m/W) and significantly higher responsivity of ∼ 3.23 mA/W. Further the sensor possesses rapid change of states as function of stepped light input (response and recovery time of ∼ 340 and ~ 550 ms) and the corresponding photocurrent and dark current show a stable plateau value. Beside reliability and noteworthy sensing parameters, the eco-friendly processing and low power operation provide a practical advantage to the fabricated organic photodetector (OPD).