Molecular size dependence of field effect in organic single crystals

TL;DR

This study investigates how molecular size influences carrier transport in organic single-crystal FETs, revealing weak size dependence and demonstrating high mobility and on/off ratios in tetracene crystals.

Contribution

It provides new insights into the molecular size effect on FET performance, especially showing minimal impact of size in tetracene compared to pentacene.

Findings

FETs on tetracene crystals show high mobility up to 0.15 cm^2/Vs

Intrinsic free carrier mobility is approximately 75 cm^2/Vs

FETs exhibit on/off ratios up to 2×10^7

Abstract

We explore the effect of molecular size on injected carrier transport. We have fabricated and characterized field effect transistors (FETs) on optically transparent single crystals of tetracene, the molecule of which is comprised of four benzene rings (BR). These FETs exhibit effective channel mobility up to 0.15 cm^2/Vs, intrinsic free carrier mobility of ~ 75 cm2/Vs, and on/off ratios up to 2*10^7. The present results show 1) the possibility of FET behavior in a transparent crystal with low intrinsic carrier density and 2) a weak dependence of performance on number of BRs, when compared to similar pentacene (5 BR) devices.