Pentacene Active Channel Layers Prepared by Spin-Coating and Vacuum Evaporation Using Soluble Precursors for OFET Applications

Abstract

Pentacene OFETs of bottom-gate/bottom-contact were fabricated with three types of pentacene organic semiconductors and cross linked Poly(4-vinylphenol) or polycarbonate as gate dielectric layer. Two different processes were used to prepare the pentacene active channel layers: (1) spin-coating on dielectric layer using two different soluble pentacene precursors of SAP and DMP; (2) vacuum evaporation on PC insulator. X-ray diffraction studies revealed coexistence of thin film and bulk phase of pentacene from SAP and thin film phase of pentacene from DMP precursors. The field effect mobility of 0.031 cm 2 /Vs and threshold voltage of −12.5 V was obtained from OFETs fabricated from SAP precursor, however, the pentacene OFETs from DMP under same preparation yielded high mobility of 0.09 cm 2 /Vs and threshold value decreased to −5 V. It reflects that the mixed phase films had carrier mobilities inferior to films consisting solely of single phase. For comparison, we have also fabricated pentacene OFETs by vacuum evaporation on polycarbonate as the gate dielectric and obtained charge carrier mobilities as large as 0.62 cm 2 /Vs and threshold voltage of −8.5 V. We demonstrated that the spin-coated pentacene using soluble pentacene precursors could be alternative process technology for low cost, large area and low temperature fabrication of OFETs.

Simultaneous Analysis of Molecular Orientation and Quantity Change of Constituents in a Thin Film Using pMAIRS

“…What is worse, SAP exhibits extremely low crystallinity in the thin film, showing no diffraction peaks . As a result, the quantity change of the chemical constituents during a thermal conversion process has never been discussed thus far, − whereas the molecular packing structure in the PEN film after completing the conversion is revealed by GIXD.…”

Review of the Common Deposition Methods of Thin-Film Pentacene, Its Derivatives, and Their Performance

“…Years later in 2012, Ochiai et al [ 55 ] fabricated an OFET device using a polymer dielectric polycarbonate (PC). The pentacene was deposited in a vacuum with a pressure of 2 × 10 −4 Pa and with the substrate temperature held at 50 °C.…”

“…The reaction with oxygen plasma in the TC device’s pentacene layer produced a derivative known as 6,13-pentacenequinone. The performance results for other thermally evaporated OTFTs are listed in Table 1 [ 55 , 57 , 58 , 59 , 60 ]. Note that the table lists only the average typical values relevant to this manuscript.…”

Inexpensive Measuring System for the Characterization of Organic Transistors

“…TIPS-pentacene (6,13-bis (triisopropylsilylethinyl) pentacene) has been used as a semiconductor in these OFETs [19]. This compound is a dark blue solid that is commercially available in the form of small crystals that can be dissolved in anisole, decane, toluene, and so on.…”