Abstract
This study mixed acetylacetone (Acac, 1, 2, and 3 mL) and graphene powder (GP, 0 wt.%, 0.001 wt.%, 0.003 wt.% and 0.005 wt.%) with TiO2 mesoporous (TiO2 powders: 20 g and particle size ~30 nm) to enhance the optoelectronic performances of dye sensitized solar cells (DSSC). Sponge-like structure TiO2 mesoporous layers is a requirement for obtaining high efficiency DSSC, which ia synthesized by spin-coating techniques. The dense TiO2 blocking layer (using peroxo-titanium complex) has a uniform, dense structure and completely adheres to the substrates to avoid charge recombination. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses of the TiO2 films display the anatase type phase with preferred orientation along the (101) direction. After being ball milled, the TiO2 mesoporous particle size almost remains unchanged. For mixing the Acac with TiO2, the Raman intensity relatively increased, and the band gap energy (Eg) value decreased from 3.223 eV (for pure TiO2) to 3.076 eV (for 2 mL Acac). Raman spectroscopy is used to evaluate the GP elements. It can be seen the intensity ratio (ID/IG) and (I2D/IG) was enhanced when the GP concentration increased. Using mixed Acac 2 mL and GP 0.003 wt.% with a TiO2 mesoporous, led to increases in the open circuit voltage (VOC), short circuit current density (JSC) and fill factor (FF). If a fluorine-doped tin oxide is used instead of an indium tin oxide glass substrate, the photovoltaic efficiency of DSSC increases from 5.45% to 7.24%.
Highlights
Dye-sensitized solar cells (DSSC) have attracted considerable attention as potential candidates for next-generation solar cells [1]
This could be due to the mixed GP with TiO2 mesoporous leading to a higher conduction band level and raised surface area, promoting the photovoltaic efficiency of DSSC
Replacing the indium tin oxide (ITO) (S9) with Fluorine-Mixed Tin Oxide (FTO) (S14, mixed Acac 2 mL, GP 0.003 wt.% with a TiO2 porous/Blocking layer/FTO) may significantly improve the number of electrons transferred from the photo-anodes to the counter electrode, leading to the JSC increase from 14.81 to 21.65 mA/cm2, and the increased photovoltaic efficiency of the DSSC from 5.45% to 7.24%
Summary
Dye-sensitized solar cells (DSSC) have attracted considerable attention as potential candidates for next-generation solar cells [1]. The spin coating technique offers simple ways to synthesize TiO2 layers, with high control of the grain sizes, surface area, morphology and structure [11,12]. The modified TiO2 graphene materials have high surface area, demonstrating appropriate dye loading for light harvesting and offering good electrolyte connection. TiO2 is a good photo-anode material in DSSC, causing greater specific surface area for adsorption of a high density of dye. It has high intrinsic band gap energy (about 3.2 eV) that can only absorb sunlight in the ultraviolet wavenumber region, resulting in low solar spectrum utilization [16]. The influence of dopant contents on the crystal phase structure, surface morphology, optical band gap and DSSC performance were analyzed in detail
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