Migration energies of Cu, In, and Ga atoms in Cu-poor Cu(In,Ga)Se₂ (CIGS) were calculated by first-principles calculations. In any Ga/(Ga+In) ratios, the migration energies of Cu in CIGS were smaller than those of the other atoms, In and Ga. The inter-atomic distances between the migrating Cu atom and the neighboring Se atoms along the migration pathway were studied in detail.

We investigated crystal structure of BaCuSeF with a space group of P4/nmm (No. 129) by Rietveld refinement of synchrotron X-ray diffraction data. The Se atom was displaced in the ab plane from the ideal position (2c). The displacement decreased with decreasing temperature. The Se atom occupied the ideal position below 125 K. The results were consistent with XAFS results.

Mixed-dimensional perovskite containing Cs₄PbI₆ phases in CsPbI₃ thin film improves stability and crystallinity. In this work, low-temperature grown mixed-dimensional perovskite thin films were spin-coated and annealed at 150℃. The compositions of CsPbI₃ and Cs₄PbI₆ ratio were shifted by annealing time from 0 to 20 minutes. The carrier lifetime of perovskite thin films trends to increase with higher XRD peak intensities of Cs₄PbI₆. It suggests that the Cs₄PbI₆ phase may inactivate in CsPbI₃ thin films.

The effect of valence band offset (VBO) on the absorber and hole-transporting layer (HTL) of CsPbI₃ perovskite thin film solar cells (PVKSCs) has been analyzed by device simulations. The device parameters used in the simulations were determined by reproducing the CsPbI₃-PVKSCs on Solar Cell Capacitance Simulator (SCAPS), which reported a conversion efficiency of 19%. The results suggest that the VBO should be in the range of -0.2 eV to +0.2 eV to achieve a conversion efficiency above 19%.

It was revealed that Average Photon Energy (APE) used as an an index of solar spectral irradiance at measurement locations blue-rich spectra. From the point of view of spectral response, a-Si, PVK, and CdTe PV technologies, which have a larger bandgap than reference sc-Si PV technology, are appropriate at the investigated locations.

Fine structured transparent solar cells were prepared by depositing n-type transparent semiconductor ZnO nanorods, a buffer layer and p-type transparent semiconductor CuBr_1-xI_x (CuBrI) thin films on glass substrates by spin-coating and dip-coating methods, and I-V measurements showed power generation.

The thin films were prepared by layer-by-layer deposition of ZnS and ZnSe nanoparticles on glass substrates. The thickness and optical constants of the prepared thin films were determined by spectroscopic ellipsometry. We demonstrate the applicability of multi-layered semiconductor nanoparticles as a material for optical thin films.

(Zn,Mg)O is applied to replace conventional ZnO as a second buffer layer of Cu₂(Sn,Ge)S₃ (CTGS) solar cells to optimize conduction band structure. Bandgap energy (E_g) of the (Zn,Mg)O films was changed from 3.20 to 3.65 eV by varying Mg/(Mg+Zn) from 0 to 0.257. The highest conversion efficiency of 4.5% was realized at the E_g of 3.55 eV owing to minimization of interfacial recombination.

To prevent exfoliation of Cu-Sn precursor, which deposited by fine channel mist CVD, from Mo coated substrate, annealed Mo coated substrate in N₂ atmosphere was used. The prevent of exfoliation was considered to be due to MoO₂ thin film grown on Mo by annealing in N₂ atmosphere which decreases difference of coefficient of thermal expansion between Cu-Sn precursor and the substrate. After sulfurization, the Cu-Sn precursors showed X-ray diffraction peaks attributed to (133), (333) and (200) peaks of monoclinic Cu₂SnS₃.

Cu₂Sn_1-xGe_xS₃(CTGS) which is composed of non-toxic elements is a promising candidate for the absorber layer of single junction solar cells. However, there are few reports on the basic properties of CTGS. Therefore, CTGS polycrystals was grown by solid state reaction and observed photoluminescence spectra.

CTS thin films were prepared via the sulfurization of Sn/Cu stacked precursors at 500-600 ℃. The observation of the surface morphology of the CTS thin film revealed that the CTS crystal grain size increased at ≥560 ℃. It was confirmed that the monoclinic phase of the CTS thin film becomes more abundant as the sulfurization temperature increases, and that the CTS thin film completely acquires a monoclinic structure at ≥570 ℃. The CTS thin-film solar cell can obtain good photovoltaic characteristics by forming a monoclinic-structured single phase and by increasing the crystal grain size.

A temperature-modulated pyroelectricity measuring system adopting ac light irradiation as a heat source for temperature modulation is developed for measuring small single crystals of molecular ferroelectrics. Estimation of pyroelectric coefficient from the pyrocurrent requires the magnitude of temperature modulation during measurements. In this study, the temperature modulation is simulated based on a one-dimensional thermal diffusion model. The validity of the calculation is confirmed by a standard sample measurement performed for a single crystal of LiNbO₃.