Photoelectronic properties of composite films based on conductive polymer PIDT-BT and single-walled carbon nanotubes

Abstract

We investigated photoelectronic properties of composite films based on semiconducting polymer poly(indacenodithiophene-co-benzothiadiazole) (PIDT-BT) and single-walled carbon nanotubes (SWCNTs). It was found that the absorbance spectra of PIDT-BT and PIDT-BT/SWCNT (1:0.3) films were in the spectral region from 200 to 800 nm, with an absorbance edge at ca. 1.71 eV. Adding of ca 30 wt% of SWCNT to the PIDT-BT polymer matrix resulted in a decrease in absorbance by a factor of 1.5. We made a hole-only device based on PIDT-BT lightly doped with carbon nanotubes. Current–voltage characteristics (I–Vs) of PIDT-BT/SWCNT (1:0.3) composite films were measured within temperature interval from 300 to 77 K in the dark and under illumination by a solar simulator. I–Vs demonstrated an increase in photocurrent under illumination at 300 K by factor of ca. 1.4–1.7 with respect to dark I–Vs. The dark I–Vs were investigated in the temperature interval from 300 to 77 K. It was found that the temperature dependence of the resistivity of PIDT-BT/SWCNT (1:0.3) films followed a power law in this temperature region. It has been established that the main charge carrier transport mechanism is the space charge limited current mechanism in the dark and the space charge limited photocurrents under illumination.