Evidence for Temperature-Dependent Electron Band Dispersion in Pentacene

TL;DR: One-atom-thick monolayer graphene provides ideal source/drain electrodes for effi cient charge injection in organic transistors assembled on plastic substrates because the synthesis of either graphene or reduced graphene oxide requires high-temperature fabrication processes.

Abstract: The energy level alignment at interfaces between conjugated organic semiconductors and metals is recognized as a key factor determining the performance of organic-based (opto)- electronic devices. [1,2] Experimentally, the hole-injection barriers (HIBs) at organic/metal interfaces can be directly determined by using ultraviolet photoelectron spectroscopy (UPS). In addition, angle-resolved UPS (ARUPS) allows molecular orientations at surfaces to be assessed. In the work reported here, we used this method to investigate interfaces between two prototypical organic semiconductors, pentacene (PEN) and perfluoropentacene (PFP), and Au. PEN can be used as the active material in organic field-effect transistors (OFETs) with a high hole mobility of up to 5.5 cm 2 V –1 s –1 . [3] The fabrication of integrated circuits also requires high-electron-mobility OFETs; this is difficult to achieve with PEN, which has reported electron mobilities of up to 0.04 cm 2 V –1 s –1 . [4] One approach to improving n-type performance of OFETs is to use PFP, resulting in high electron mobilities of more than 0.2 cm 2 V –1 s –1 . [5] Commonly, Au is used as the source and drain contact metal in OFETs. Therefore, the interface ener-getics between organic semiconductors and Au are of interest, since charges have to be transported across these interfaces and minimized contact resistance is aimed at. While a number of reports are already available on PEN/Au interfaces, nothing is yet known about PFP/Au. Moreover, published work on PEN/Au interfaces reveals controversial values for the HIB, ranging from ca. 0.5 to 0.9 eV for various polycrystalline [6–9] and single-crystal [10,11]

TL;DR: The present findings indicate that controlling organic-graphene heterointerface could provide a design strategy of organic solar cell architecture for boosting photon harvesting and show a 5 times increment in the maximum power conversion efficiency than the equivalent devices without a graphene layer.

TL;DR: The valence-band structures of single-crystal pentacene and the temperature dependence of their energy-momentum dispersion relations are successfully demonstrated using angle-resolved ultraviolet photoelectron spectroscopy (ARUPS).

TL;DR: In this article, the authors present new insight into conduction mechanisms and performance characteristics, as well as opportunities for modeling properties of organic thin-film transistors (OTFTs) and discuss progress in the growing field of n-type OTFTs.

TL;DR: In this article, the hole mobility for the organic conductor pentacene was obtained at room temperature and at 225 K. The number of traps was reduced by two orders of magnitude compared with conventional methods.

TL;DR: Research in organic electronics has included advances in materials, devices, and processes as mentioned in this paper, which are enabling the incorporation of organic electronic components in products including OLED displays and flexible electronic paper.

TL;DR: In this paper, a hole mobility for the organic conductor pentacene of 35 cm2/Vs at room temperature increasing to 58 cm2 /Vs at 225k was obtained.