Investigation of electronic trap states in organic photovoltaic materials by current-based deep level transient spectroscopy

TL;DR

This study uses current-based deep level transient spectroscopy to identify and analyze trap states in organic photovoltaic materials, revealing specific trap energies in P3HT, PCBM, and their blend, which impact device performance.

Contribution

It provides detailed characterization of trap states in key organic photovoltaic materials using a novel current-based DLTS method.

Findings

Trap energies of 87 meV in P3HT and 21 meV in PCBM.

Complex emission spectra in P3HT:PCBM blend with energies between 30-160 meV.

Identification of multiple emission rate bands indicating diverse trap states.

Abstract

Current-based deep level transient spectroscopy was used to study trap states in poly(3- hexylthiophene-2,5-diyl) (P3HT), [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) and P3HT:PCBM blend. The obtained spectra showed traps of 87 meV activation energy in pure P3HT and 21 meV for PCBM. The blend shows a complex emission rate spectrum consisting of several different emission rate bands in the range of (0.1-30) s^-1, yielding activation energies between about 30 meV and 160 meV.