Tuning the charge transport and photo-physical behavior in hybrid poly(3-hexylthiophene) and silver sulfide quantum dot based nanocomposite devices

Abstract

Abstract The charge transport properties are studied in hybrid thin films composed of poly (3-hexylthiophene) polymer (P3HT) and silver sulfide (Ag2S) quantum dots (QDs) by temperature and photo-dependent current-voltage (J–V) characteristics. A complete reversal in J-V characteristics is observed in ITO/Nanocomposite/Au devices as the QDs’ concentration in the polymer matrix reaches to 50 wt percentage (wt. %). A detailed study of charge injection through ITO exhibits a transition in transport mechanism from direct tunnelling to thermionic emission with increasing QDs up to 20 wt % and further governed by space charge limited conduction for 50 and 80 wt % devices. Charge injection through Au shows the transition from Poole-Frenkel to thermionic emission as the QDs surpasses 10 wt % in polymer matrix. The effect of injection barrier and charge transfer phenomena on the transport properties are discussed in details by photoluminescence and photocurrent measurements.