Space Charge Limited Transport and Time of Flight Measurements in Tetracene Single Crystals: a Comparative Study

TL;DR

This study compares space charge limited current spectroscopy and time of flight measurements to analyze electronic transport in tetracene single crystals, revealing mobility characteristics and trap effects.

Contribution

It demonstrates the effectiveness of combining $I$-$V$ and time of flight methods to characterize charge transport and trap states in organic crystals.

Findings

Room-temperature hole mobility ~1 cm$^2$/Vs

Mobility increases as temperature decreases

Deep and shallow traps characterized and quantified

Abstract

We report on a systematic study of electronic transport in tetracene single crystals by means of space charge limited current spectroscopy and time of flight measurements. Both $I$-$V$ and time of flight measurements show that the room-temperature effective hole-mobility reaches values close to $\mu \simeq 1$ cm$^2$/Vs and show that, within a range of temperatures, the mobility increases with decreasing temperature. The experimental results further allow the characterization of different aspects of the tetracene crystals. In particular, the effects of both deep and shallow traps are clearly visible and can be used to estimate their densities and characteristic energies. The results presented in this paper show that the combination of $I$-$V$ measurements and time of flight spectroscopy is very effective in characterizing several different aspects of electronic transport through organic crystals.