Evaluation of Limiting Factors Affecting Photovoltaic Performance of Low‐Temperature‐Processed TiO₂ Films in Dye‐Sensitized Solar Cells

Abstract

Limiting factors affecting photovoltaic performance of dye-sensitized solar cell employing low-temperature-processed TiO2 films were investigated. TiO2 films were prepared at a low temperature of 200 °C using the normal alcohol-containing binder-free TiO2 paste (LT200). Their photovoltaic performance was compared to a high-temperature (550 °C) annealed TiO2 film prepared using a polymer binder containing TiO2 paste (HT550). Compared to the proportional increase in conversion efficiency with TiO2 film thickness upto 14 μm for HT550, the increase in efficiency was terminated at relatively smaller thickness of about 8 μm for LT200 mainly due to unaugmented photocurrent. From the transient photocurrent-voltage studies, the electron transport rate was found to be almost identical, while charge recombination was one order of magnitude faster for LT200. Consequently, the electron diffusion length was more than 2-3 times shorter for LT200 than for HT550. Electron diffusion length and electron life time obtained from electrochemical impedance analysis were well consistent with those observed from transient measurement. Density of states (DOS) was evaluated to be shallow and narrow in LT200, which was responsible for limiting photovoltaic performance in the low-temperature processed TiO2 film.

Fabrication and characterization of novel hybrid nanocomposites with application in solar cells

“…This observation was not surprising, owing to the high surface resistivity of the polymer substrates compared to the glass ones, as well as to the obligatory low-temperature manufacturing process of the polymer working electrodes, which led to unsuitable characteristics of the anode semiconductor. According to the literature, electron diffusion length is much shorter for the low-temperature processed TiO2 films compared to the high-temperature ones [459,593]. This is due to the decreased compactness of the TiO2 semiconductor, different TiO2 crystal structure, and increased charge recombination rate at TiO2/electrolyte interface of the former compared to the latter, which were also observed in the present investigation.…”

Role of Hydroxyl on Conductivity Switching of Poly(ethylene oxide)/TiO2 Electrical Bistable Devices

“…To verify this assumption, Fourier‐transform infrared (FT‐IR) spectra measurements were conducted on the films prepared by heating at 120 and 250 °C. The results show that a series of the absorption peaks in the range of 3000–3800 cm −1 can be significantly weakened by heating, and these peaks are correspondent to the surface hydroxyl groups . It should be mentioned that the absorption peaks in the range of 3000–3800 cm −1 can also be attributed to bulk hydroxyl groups.…”

Recent advances in the development of flexible dye-sensitized solar cells: fabrication, challenges and applications-a review

“…So, to improve the inter-nanoparticles connection, mechanical stability, and high-quality film-substrate adhesion, the TiO 2 coated film needs additional processing. Several techniques has been used to obtain high efficiency of the flexible DSSCs such as hydrothermal crystallization or chemical sintering [81,98,123], blocking layer (BL) [133,134], UV-Ozone treatment [96,135,136], UV radiation exposed [124,137], microwave heating [138], mechanical compression [128,139], cold isostatic pressing (CIP) [121,140], lift-off [141] and building block [142] etc. In flexible substrates a major drawback is the formation of cracks and weak inter-particle connectivity of TiO 2 film [94].…”