Preparation of porous nanoparticle TiO2 films for flexible dye-sensitized solar cells

Abstract

A TiO 2 paste was prepared by mixing commercial TiO 2 (P25), ethanol, distilled water and a small amount of Ti (IV) tetraisopropoxide (TTIP), following by a hydrothermal treatment. Before hydrothermal treatment, a stirring for 48 h can prevent cracking TiO 2 films. TTIP significantly promote the chemical connection between TiO 2 particles and its adherence to the substrate, the TTIP amount of 6 mol% is suitable. UV irradiation can remove some impurities and water from the TiO 2 film with an optimal time of 2 h. Transmission electron microscopy, X-ray diffraction, scanning electron microscopy and photovoltaic tests are characterized and measured. Short Since the prototype of dye-sensitized solar cell (DSSC) was first reported in 1991, it has received widely interest because of its low cost and simple preparation, and DSSCs with photoelectric conversion efficiencies of 11% have been achieved [1,2]. DSSC consists of a conducting substrate, nano-porous oxide film, dye sensitizer, electrolyte and counter electrode. The conducting substrate usually is made of a transparent conductive glass, which limit DSSCs practical applications because of its weight, frangibility and high cost. DSSCs based on flexible substrate have attracted wide interest due to its merits, such as light weight, good flexibility, impact-proof, lower cost [3,4]. Besides, their shapes or surfaces can be devised and constructed, the technique of large-scale continuous production and rapid coating can be used, which further decrease the production cost [3][4][5][6]. The conventional method for obtaining an efficient electrode materials is the high-temperature calcination of nanocrystalline semiconductor particles. Colloidal pastes containing organic additives are often used, with the latter essential to suppress particle agglomeration and reduce stress during calcination. Crack-free well-adhered films with optimal mesoporous structure can then be obtained. Hightemperature annealing (> 400°C) can remove organic additives and promote chemical interconnection between particles to establish an electrical connection [7]. The requirement of high temperature clearly excludes using plastic-film substrates, and the development of low-temperature methods is necessary for the realization of flexible DSSCs. The current performance of such films is much lower than those prepared conventionally as above. The low-temperature preparation of TiO 2 films can result in incomplete interconnection with adjacent particles and poor adherence of the film to the substrate. Much efforts have been devoted to overcome the problems associated with preparing porous

The Basic Research on the Dye-Sensitized Solar Cells (DSSC)

“…It has the best condition for sintering and the most stable power produced besides having the uniformity of the film thickness and good surface condition. The mesoporous photoelectrodes films composed of small-sized TiO2 nanocrystalline particles have the advantages of providing a large surface for greater dye adsorption and facilitating electrolyte diffusion within their pores [27].…”

Suppression of charge recombination by application of Cu2ZnSnS4-graphene counter electrode to thin dye-sensitized solar cells

“…Dye-sensitized solar cells (DSSC) have attained momentous interest for solar energy conversion, due to their ease of fabrication, low cost compared to other photovoltaics [1][2][3][4][5]. Typically, a DSSC consist of four parts: dye-sensitizer, n-type semiconductor photoanode, a redox electrolyte, and a counter electrode (CE).…”

The effect of ethylene glycol/citric acid molar ratio in the initial precursor of TiO2 nanoparticle paste synthesized by a polymerizable complex method on the photovoltaic properties of dye-sensitized solar cells

“…This is because of the available fast printing techniques [17]. Often, in order to improve the interconnection between TiO 2 nanoparticles and the adhesion of TiO 2 mesoporous layer to FTO, the sol-gel method has been employed in the synthesis of TiO 2 nanoparticle paste [18][19][20][21][22].…”