Conduction type control from n to p type for organic pigment films purified by reactive sublimation

Abstract

The effects of purification by reactive sublimation technique and bromine doping on the Fermi level and the photovoltaic properties of n-type perylene pigment films were investigated. Photovoltage arisen from the Schottky junction between n-type perylene pigment film and Au increased significantly by repeating the train sublimation under methylamine gas atmosphere. This phenomenon was revealed to be due to the negative shift of the Fermi level resulting from the effective removal of unknown but specific impurity acting as an acceptor by reactive sublimation. On the other hand, by bromine doping, Fermi level of the pigment film shifted largely to a positive direction and reached the nearby valence band, while the direction of photocurrent flow arising from the Schottky junction with Au was reversed. This result is a clear demonstration of alternating the type of conduction from n type to p type. This means that the pn control of organic semiconductors is possible.

High mobility n-channel organic thin-film transistors and complementary inverters

“…The relevant energy levels ͑referenced to the vacuum level͒ for charge transport in PTCDI-C 13 H 27 films have been estimated to be similar to those of PTCDI-C x H 2x+1 with x =0 ͑3.4 and 5.4 eV for electrons and holes, respectively͒ 33 and are in relative agreement with energy levels predicted by quantum chemical calculations for PTCDI derivatives. 28 Gold ͑Au͒, calcium ͑Ca͒, and silver ͑Ag͒ have been previously demonstrated to provide for electron injection into PTCDI-C x H 2x+1 films and Chesterfield et al 32 reported no clear dependence of the mobility on the work function of the contact metal.…”

Tuning Optoelectronic Properties of Ambipolar Organic Light‐ Emitting Transistors Using a Bulk‐Heterojunction Approach

“…[34] The HOMO level of T5 lies at about -5.3 eV [37] and the LUMO level at about -2.8 eV. [37] The HOMO and the LUMO levels of P13 are estimated to be ∼ -5.4 and ∼ -3.4 eV, [38] respectively.…”

Electrical shorting of organic photovoltaic films resulting from metal migration

“…As test materials, we adopted perylene pigment ͑Me-PTC, Fig. 1͒ as an organic film, as this has been used for organic solar cells [7][8][9] together with Au as a metal electrode.…”