Titanium dioxide application in solar cells

Abstract

Abstract:Extensive research has been performed in solar cells field, due the fact that the main current energy sources are derived from finite fossil fuels, and cause environmental problems. In this perspective the sun can be seen as the energy future of the planet, being the most abundant renewable energy source. The solar cell basic operation is based on the semiconductors ability in converting sunlight into electricity when exposed to sun radiation. A semiconductor that has been highlighted in solar cells application is titanium dioxide (TiO 2 ), due to its intrinsic properties, such as a wide bandgap, transparence to visible light, photostability, a low cost material, and others. Among the main types of solar cells applying TiO 2 are the dye-and the quantum dots-sensitized solar cells, and perovskites cells. In this review the main aspects related to synthesis, textural and morphological properties of TiO 2 of interest for application in solar cells are discussed.Keywords: Titanium dioxide; semiconductor; solar cells. ResumoExtensivas pesquisas têm sido desenvolvidas com células solares (CSs), uma vez que as principais fontes de produção de energia atuais são derivadas de combustíveis fósseis finitos e que causam problemas ambientais. Nesta perspectiva, o sol pode ser visto como o futuro energético do planeta, sendo a fonte de energia renovável mais abundante. O funcionamento básico de uma CS se baseia na habilidade em que os semicondutores apresentam de converter a luz solar em eletricidade, quando expostos à radiação solar. Um dos semicondutores que têm se destacado em CSs é o dióxido de titânio (TiO 2 ), devido às suas propriedades intrínsecas, como uma larga banda proibida, transparência à luz visível, fotoestabilidade, baixo custo, dentre outras. Dentre os principais tipos de CSs que utilizam TiO 2 , estão as CSs sensibilizadas por corantes, por pontos quânticos e as de perovsquitas. Nesta revisão os principais aspectos relacionados à síntese, propriedades texturais e morfológicas do TiO 2 de interesse para aplicação em CSs são discutidos.

Recombination Study of Dye Sensitized Solar Cells with Natural Extracts

“…27,30 In the case of the IMVS technique, the response is semicircular, and the phase lag is caused by the relaxation of electrons by back reaction with cations, in the hole conductor matrix, which are assumed to be in excess. 30,31 The τ r can be obtained from the IMVS plot according to the following equation: 18 (2) in which f r is the minimum point frequency (in Hz) of the IMVS response. The order of magnitude of the mean transit time for photogenerated electrons can be obtained from the frequency minimum in the complex plane IMPS plot, as equation 3: 18 (3) in which f c is the minimum point frequency (in Hz) of the IMPS response.…”

“…1 Solar energy is an important resource because of its inexhaustibility and pollution-free character. 1,2 Dye-sensitized solar cells (DSSCs) are devices that can convert sunlight to electricity by a photovoltaic effect, theoretically exceeding the Shockley-Queisser limit. 2 Light harvesting is provided by the use of a semiconductor material with an ideal sensitizer, which can absorb the light and eject electrons to an excited state (lowest unoccupied molecular orbital (LUMO) level; Figure 1).…”

“…1,2 Dye-sensitized solar cells (DSSCs) are devices that can convert sunlight to electricity by a photovoltaic effect, theoretically exceeding the Shockley-Queisser limit. 2 Light harvesting is provided by the use of a semiconductor material with an ideal sensitizer, which can absorb the light and eject electrons to an excited state (lowest unoccupied molecular orbital (LUMO) level; Figure 1). 3,4 The use of an electrolyte is necessary to intermediate the charges and allow an electron flow.…”

“…3,4 The use of an electrolyte is necessary to intermediate the charges and allow an electron flow. [5][6][7] The most promising method for light conversion in DSSCs is via nanocrystalline TiO 2 , sensitized with ruthenium complexes, such as cis-[Ru (2,2'-bipyridil-4,4'-dicarboxylic acid) 2 (NCS) 2 ] (N3) and (Bu 4 N) 2 [Ru (2,2'-bypiridil-4,4'-dicarboxylic acid) 2 (NCS) 2 ] (N719). However, these molecules have a high cost that gives impetus to the search for lower-cost materials such as natural dyes, containing flavonoids, as anthocyanins.…”

COMPARATIVE STUDY OF TiO2 AND ZnO APPLICATION IN HYBRID SOLAR CELLS USING COPOLYMER P3OT/P3MT

“…3 Semiconductor oxides such as TiO 2 , ZnO, Nb 2 O 5 , and CeO 2 are used in these devices because they possess good photochemical properties, thermodynamic stability, great crystallinity a form transparent films invisible light and presents band gap in the order of 3 to 3.4 eV. 4,5 They are often used in combination with photosensitizing materials because it is necessary to take advantage of some effective interactions between both materials. 5 Poly (3-alkylthiophenes) (P3ATs) are organic polymers with conjugated structures, which make them conductive and luminescent.…”