ABSTRACT
Connection of SnO2 particles by simple UV irradiation in air yielded cassiterite SnO2 porous films at low temperature. XPS, FTIR, and TGA-MS data revealed that the UV treatment has actually removed most of the organics present in the precursor SnO2 colloid and gave more hydroxylated materials than calcination at high temperature. As electrodes for dye-sensitized solar cells (DSCs), the N3-modified 1-5 µm thick SnO2 films showed excellent photovoltaic responses with overall power conversion efficiency reaching 2.27% under AM1.5G illumination (100 mW cm⻲). These performances outperformed those of similar layers calcined at 450 °C mostly due to higher V(oc) and FF. These findings were rationalized in terms of slower recombination rates for the UV-processed films on the basis of dark current analysis, photovoltage decay, and electrical impedance spectroscopy studies.
ABSTRACT
SnO2 translucent monolith ionogels were obtained by a sol-gel processing using bis(2-methylbutan-2-oxy)di(pentan-2,4-dionato)tin as a precursor in the presence of various ionic liquids: [BMI][Br], [BMI][TFSI], [BMI][BF4]. The confinement of ionic liquids within the gels was evidenced by Differential Scanning Calorimetry, FTIR and FT-Raman spectroscopy. The ionic liquids could be efficiently washed off, which resulted in supermicroporous solids. Calcination in air at 550 degrees C of the dried monoliths resulted in nanoporous nanocrystalline cassiterite tin dioxide particles with crystallite sizes of about 8-12 nm and mean pore sizes around 5 nm.