High-Mobility Transistors Based on Single Crystals of Isotopically Substituted Rubrene-d₂₈

Abstract

We have performed a comprehensive study of chemical synthesis, crystal growth, crystal quality, and electrical transport properties of isotopically substituted rubrene-d 28 single crystals (D-rubrene, C 42 D 28 ). Using a modified synthetic route for protonated-rubrene (H-rubrene, C 42 H 28 ), we have obtained multigram quantities of rubrene with deuterium incorporation approaching 100%. We found that the vaporgrown D-rubrene single crystals, whose high qualities were confirmed by X-ray diffraction and atomic force microscopy, maintained the remarkable transport properties originally manifested by H-rubrene crystals. Specifically, field-effect hole mobility above 10 cm 2 V −1 s −1 was consistently achieved in the vacuum-gap transistor architecture at room temperature, with an intrinsic band-like transport behavior observed over a broad temperature range; maximum hole mobility reached 45 cm 2 V −1 s −1 near 100 K. Theoretical analysis provided estimates of the density and characteristic energy of shallow and deep traps presented in D-rubrene crystals. Overall, the successful synthesis and characterization of rubrene-d 28 paves an important pathway for future spin-transport experiments in which the H/D isotope effect on spin lifetime can be examined in the testbed of rubrene.

Negative isotope effect for charge transport in acenes and derivatives – a theoretical conclusion

“…46 However, in 1973, they overturned this result and reported a 10% negative IE in the c 0 direction and zero effect in the a and b directions. 7 We recently proposed using the IE effect to probe the quantum nuclear tunneling effect in organic semiconductors such as N,N 0 -n-bis(n-hexyl)-naphthalene diimide (NDI) and N,N 0 -n-bis(n-octyl)-perylene diimide (PDI). 19 Very recently, Frisbie et al reported a negligible IE for hole transport in all-deuterated rubrene.…”

From stretchable to reconfigurable inorganic electronics

“…Additional examples of organic-based devices with high mobilities include the work by Podzorov et al in 2003, who demonstrated a mobility magnitude of 8 cm 2 /Vs by optimizing the fabrication process of rubrene-based single-crystal organic field-effect transistors [24] . A decade later, Wei Xie et al showed a transistor based on rubrene-d28 single crystals with a consistent mobility of 10 cm 2 /Vs at room temperature [25] , and in the same year, Il Kang et al built an OTFT with a mobility of 12 cm 2 /Vs through side-chain engineering of two polymer semiconductors (P-29-DPPDBTE and P-29-DPPDTSE) [26] . Note that predominant organicbased devices are p-type and thus the reported mobilities correspond to holes; electron mobilities are usually several factors lower (the highest electron mobility of 6.3 cm 2 /V.s reported was achieved with the donor-acceptor polymer PDBPyBT by Bin Sun et al) [27] .…”

Recent trends in crystal engineering of high-mobility materials for organic electronics

“…SCFETs were fabricated and showed ambipolar transport as expected. Although device architecture has not been fully optimized, maximum hole (electron) mobilities [43]. The X ray diffraction data indicate that the D rubrene maintains the same crystal structure and unit cell parameters as the H rubrene crystal.…”