Cu2Zn1–x Cdx Sn(Se1–y Sy)4 monograin powders with different x ‐ and y ‐values were prepared from binary compounds in the liquid phase of flux material (KI) in evacuated quartz ampoules. All the materials had uniform composition and p‐type conductivity. PL spectra (10 K) of the as grown Cu2Zn1–x Cdx Sn(Se)4 monograin powders showed one PL band with peak position around 0.85 eV which shifted linearly to the lower energy side with increasing Cd content. Cu2ZnSnS4 material showed asymmetrical PL band at 1.31 eV attributed to band‐to‐tail recombination. RT Raman spectra of Cu2ZnSnSe4 revealed two main peaks at 196 cm–1 and 173 cm–1 and a third less intensive peak with varying peak position in the region 231–253 cm–1. Raman spectra of Cu2ZnSnS4 showed an intensive peak at 338 cm–1 and additional peaks at 287 cm–1 and 368 cm–1. Narrow sieved fractions of grown powders were used as absorber materials in monograin layer (MGL) solar cell structures: graphite/ Cu2Zn1–x Cdx Sn(Se1–y Sy)4/CdS/ZnO. The best so far solar cell that was based on the Cu2Zn0.8Cd0.2SnSe4 had open circuit voltage 422 mV, short circuit current 12 mA/cm2 and fill factor 44%. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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TiO2 thin films with different titanium isopropoxide (TTIP):acetylacetone (AcacH) molar ratios in solution were prepared by the chemical spray pyrolysis method. The TTIP:AcacH molar ratio in spray solution varied from 1:3 to 1:20. TiO2 films were deposited onto the glass substrates at 350 °C and heat-treated at 500 °C. The morphology, structure, surface chemical composition, and photocatalytic activity of the obtained TiO2 films were investigated. TiO2 films showed a transparency of ca 80% in the visible spectral region and a band gap of ca 3.4 eV irrespective of the TTIP:AcacH molar ratio in the spray solution. TiO2 films consist of the anatase crystalline phase with a mean crystallite size in the range of 30–40 nm. Self-cleaning properties of the films were estimated using the stearic acid (SA) test. A thin layer of 8.8-mM SA solution was spin-coated onto the TiO2 film. The degradation rate of SA as a function of irradiation time was monitored by Fourier-transform infrared spectroscopy (FTIR). An increase in the TTIP:AcacH molar ratio from 1:4 to 1:8 resulted in a ten-fold increase in the photodegradation reaction rate constant (from 0.02 to the 0.2 min−1) under ultraviolet light and in a four-fold increase under visible light.

The author is mainly responsible for this work. The author developed the idea, designed & conducted the experiments and measurements, and analysed the data. The author was responsible for writing the manuscript, communicating with the journal editor and answering to the reviewers' queries. Publication 2: Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film. The author is mainly responsible for this work. The author designed & conducted the experiments, fabricated & measured the devices, and analysed the data. The author was responsible for writing the manuscript, communicating with the journal editor, and answering to the reviewers' questions. Publication 3: Synergistic Effect of Single-Walled Carbon Nanotubes and PEDOT:PSS in Thin Film Amorphous Silicon Hybrid Solar Cell. The author is mainly responsible for conceptualization of the idea, design of experiments, measurements, data analysis, and jointly writing the paper. The author was responsible for answering to the reviewers' questions. Publication 4: Rational design of highly efficient flexible and transparent ptype composite electrode based on single-walled carbon nanotubes. The author is mainly responsible for this work. The author designed & conducted the experiments, fabricated & measured the devices, and analysed the data. The author was responsible for writing the manuscript, and answering to the reviewers' questions. Publication 5: Review: Hybrid heterojunction solar cells based on singlewalled carbon nanotube and amorphous silicon thin films. The author is mainly responsible for this work and writing the paper.

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