Copolymerization of EDOT with Pyrrole on TiO₂ Semiconductor Films by One-Step Reaction, Structure-Dependent Electronic Properties, and Charge Conduction Models of the Composite Films

Abstract

We used the photoexcited TiO2 films to initiate the copolymerization of 3,4-ethylenedioxythiophene with pyrrole, aiming to develop an organic/inorganic heterojunction. Specular reflection infrared spectroscopy analysis was used to monitor the process of polymerization and indicated that the copolymers directly grew on the TiO2 substrate. Dissecting the copolymers with ultraviolet photoelectron spectroscopy revealed the evolution of the valence-band electronic structures. Moreover, the resulting copolymer/TiO2 heterojunctions were investigated using electrochemical impedence and X-ray photoelectron spectroscopy. The Al/poly(3,4-ethylenedioxythiophene-co-pyrrole)/TiO2/ITO heterojunction device that was prepared from the hybrid film exhibited a conspicuous rectification. The heterojunction device was also explored with respect to the conduction models.

Fabrication of polythiophene–TiO2 heterojunction solar cells coupled with upconversion nanoparticles

“…Then the reactor was subjected to the UV light of 365 nm for various reaction times. The other reaction conditions were identical to those of our previous work [6,9]. The as-prepared PTh-TiO 2 :UCNP film was rinsed with ethanol and then dried by nitrogen flow.…”

“…Heterojunctions consisting of p-conjugated polymers and inorganic semiconductor nanocrystals have attracted increasing attention owing to their use in a variety of organic electronic fields [1][2][3][4][5][6][7]. When the heterojunctions are applied in photovoltaic devices, the polymers work as donors to absorb sunlight and transport holes, while the inorganic semiconductors function as acceptors to transport electrons [8].…”

“…Moreover, to facilitate the charge transfer, Xu et al synthesized the triethoxy-2-thienylsilane functionalized TiO 2 and employed triethoxy-2-thienylsilane as the linker to connect P3HT with TiO 2 [21]. In contrast to these stepwise strategies, we have previously reported a one-step photopolymerization which adopts the photoexcited nanocrystalline semiconductors as initiators [6,7]. In particular, the synthesized polymers directly grow on the surface of the nanocrystals and are bound to the nanocrystals, leading to the intimate heterojunction interface.…”

“…In particular, the synthesized polymers directly grow on the surface of the nanocrystals and are bound to the nanocrystals, leading to the intimate heterojunction interface. By using this novel method, we have obtained the heterojunction film of polypyrrole on the semiconductor TiO 2 nanoarray, and conjugated copolymer poly(3,4-ethylenedioxythiophene-copyrrole) on the semiconductor TiO 2 substrate [6,7]. The assynthesized heterojunction films have been investigated in respect to the electronic properties [6,7].…”

High performance resistive switching memory organic films prepared through PPy growing on graphene oxide substrate

“…In previous work, we have reported novel polymerizations using the oxide semiconductors as the photo-initiators. By using this method, we have synthesized the photovoltaic PPy-TiO 2 composite film [22] and polythiophene-WO 3 composite film [23], photoconductive PVK-ZnO [24], and the composite film with the pyrrole copolymers growing on a TiO 2 substrate [25]. Mechanism investigations have correlated the initiation reactions to the photocatalysis [26].…”