Dye Capped Semiconductor Nanoclusters. Role of Back Electron Transfer in the Photosensitization of SnO₂ Nanocrystallites with Cresyl Violet Aggregates

Abstract

Adsorption of a cationic dye, cresyl violet, on SnO 2 and SiO 2 nanoclusters and nanocrystalline thin films results in the formation of H-aggregates. These dyes are photochemically and electrochemically active and extend the photoresponse of large bandgap semiconductors such as SnO 2 . Photocurrent generation in dye capped nanocrystalline films of SnO 2 has been demonstrated with visible light excitation. A photon-tophotocurrent generation efficiency around 1% has been observed at 510 nm. Back electron transfer between the photoinjected electron and the oxidized sensitizer plays an important role in controlling the efficiency of net electron transfer. Transient absorption and microwave absorption measurements of the dye aggregate capped SnO 2 films suggest that the back electron transfer is multiexponential and most is completed within a few hundred nanoseconds. The activation energy of the back electron transfer process is very low (∼1.7 kJ/mol).

Parameters Influencing Charge Recombination Kinetics in Dye-Sensitized Nanocrystalline Titanium Dioxide Films

“…Note also that many previous literature reports of charge recombination have used excitation intensities >2mJ/cm 2 , and may therefore be complicated by such nonlinear issues. [14][15][16] To avoid such nonlinear effects, all of our experiments were conducted using excitation powers corresponding to one photoinduced dye cation per TiO 2 particle, as we have employed previously.…”

Interaction of N-(2-Methyl Thio Phenyl)-2-Hydroxy-1-Naphthaldimine with Tin Dioxide Nanoparticles: A Spectroscopic Approach

“…Our group has studied spectral investigation of NMTHN by silver nanoparticle using fluorescence quenching [14]. Although there are many studies on the photochemical and fluorescence behavior of organic dyes on SnO 2 thin film, there is none for SnO 2 NPs on the fluorescence quenching of Schiff base in methanol medium [15][16][17][18]. In the present study, using optical absorption and fluorescence emission techniques the effect of SnO 2 NPs on NMTHN has been investigated.…”

Quantum Chemical Designing of Efficient Sensitizers for Dye Sensitized Solar Cells

“…Efficiency of organic sensitizers decreases due to dye aggregation and charge recombination. 9 It has been established that the triphenylamine (TPA) 10 derivatives as electron donor and cyanoacetic acid moiety as electron acceptor are better options to improve the efficiency. 9 It is estimated that TPA can restrain the cationic charge from the semiconductor surface therefore block the recombination.…”

“…9 It has been established that the triphenylamine (TPA) 10 derivatives as electron donor and cyanoacetic acid moiety as electron acceptor are better options to improve the efficiency. 9 It is estimated that TPA can restrain the cationic charge from the semiconductor surface therefore block the recombination. TPA also has a characteristics steric hindrance that can put off undesirable dye aggregation at the semiconductor surface.…”