Photoinduced Formation of Polythiophene/TiO₂ Nanohybrid Heterojunction Films for Solar Cell Applications

Abstract

Formation of nanostructured polythiophene/TiO 2 heterojunction films, using photoinduced polymerization of thiophene inside TiO 2 nanopores, was investigated. The resultant film possesses nanohybridization and electronic connection within the TiO 2 nanoporous domain. Photopolymerization proceeded in three stages: (i) photoexcitation of bithiophene covalently attached to the TiO 2 surface, (ii) an electron injection reaction from the surface attached thiophene to the TiO 2 , and (iii) an electron transfer from a thiophene reactant in an electrolyte to the surface-attached bithiophene. Initial rapid photopolymerization and subsequent slow polymer growth were explained by analysis of a series of experiments, e.g., with respect to light irradiation time, applied bias, electrolyte types, thiophene reactant type, and their morphology. Electrochemical measurements for the bithiophene adsorbed on TiO 2 revealed a wide distribution of redox potentials. This was explained by influence of the local electric field on the TiO 2 surface in addition to strong interaction between the surfacebound bithiophene and the TiO 2 . The nanohybrid film was applied to a sensitized-type photoelectrochemical solar cell, substantiating direct application of the nanohybrid film to electronic devices. The solar cell performance was closely associated with the interfacial structure in the nanohybrid film and the photopolymerization degree.

The role of (photo)electrochemistry in the rational design of hybrid conducting polymer/semiconductor assemblies: From fundamental concepts to practical applications

“…From a polymerization perspective, the benefits M a n u s c r i p t of the previously described geometries are merged in this configuration, namely the large surface area of the nanoparticulate film, and electrochemical control with over the polymerization. In this vein, TiO 2 /PPy [221][222][223], TiO 2 /PEDOT [224,225], TiO 2 /PT [15,226], and ZnO/PMT [227] hybrids were realized. In some cases, carboxyl groupcontaining thiophene-derivatives were initially grafted onto the TiO 2 surface and subsequent polymer growth was initiated through these moieties.…”

“…In these cases, the precursor of the polymer (e.g., a dimer or oligomer) linked to the SC surface is photoexcited, and while the photogenerated e -is transferred to the SC, the oxidized precursor reacts with a further monomer/dimer [226,228].…”

Synthesis of polythiophene/graphene oxide composites by interfacial polymerization and evaluation of their electrical and electrochemical properties

“…Among them, PTh is considered as one of the most promising materials due to its low cost, high environmental stability, good electrical conductivity and other specific properties. It has large areas of applications in electronics, photovoltaic cells, electrocatalysis, corrosion protection, sensors and actuators . A variety of nanofillers such as metals and metal oxides has been introduced into the PTh matrix for various improvements in properties including electrical conductivity and thermomechanical properties .…”

Photochemical formation of semiconducting nanostructures

“…Photopolymerization of thiophene and its derivatives in the pores of nanocrystalline TiO 2 films leads to the formation of TiO 2 /electroconducting polymer composites, in which the effectiveness of electron phototransfer from the electroconducting polymer to the TiO 2 nanoparticles exceeds 99% [225]. The polymerization of thiophene is initiated by photoinduced electron transfer from adsorbed 2,2¢-bithiophene-5-carboxylic acid to the TiO 2 nanoparticles.…”