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In this paper, structural and photovoltaic properties of perovskite CH3NH3PbI3-xClx solar cells added with ammonium iodide (NH4I) are reported. The CH3NH3PbI3-xClx photovoltaic cells were fabricated by a hot air blow-assisted spin-coating method. By addition of NH4I, photovoltaic performance of the CH3NH3PbI3-xClx cell fabricated by the hot air blow-assisted spin-coating method was improved. The microstructure analysis of the resulting cells showed that the NH4I− added CH3NH3PbI3-xClx film was highly oriented along the (100) plane. Moreover, morphological changes of the NH4I− added CH3NH3PbI3-xClx film due to NH4I addition were also observed. The improvements of the photovoltaic performance, the crystal orientation, and the morphological changes of the CH3NH3PbI3-xClx are attributed to NH4I addition.

Photovoltaic properties of copper (Cu)-doped perovskite (CH3NH3PbCuxI3+x) photovoltaic devices with different Cu content were investigated. The CH3NH3PbCuxI3+x films were polycrystalline with a tetragonal system, and their lattice constants and crystallite size varied with Cu doping. Compared to conversion efficiencies of non-doped CH3NH3PbI3 photovoltaic device, those of CH3NH3PbCuxI3+x photovoltaic devises increased. The improvement of photovoltaic properties was attributed to partial substitution of Cu at the Pb sites.

Surface and inside of silicon (Si) spheres prepared by a powder melting method were investigated. The lattice constant of the inside of Si spheres was larger than that of the surface of Si spheres, which was due to interstitial atoms trapped at gettering sites. To obtain the evidence for existence of the impurities, composition analysis was carried out. Florescence spectra of the surface and inside of Si spheres exhibited some information on impurities in both Si spheres.

Effects of AsI3 and NH4Cl addition to perovskite CH3NH3PbI3 precursor solutions on photovoltaic properties were investigated. TiO2/CH3NH3Pb(As)I3(Cl)-based photovoltaic devices were fabricated by a spin-coating technique, and the microstructures of the devices were investigated by X-ray diffraction and scanning electron microscopy. Current density-voltage characteristics and incident photon-to-current conversion efficiencies were improved by a small amount of As- and Cl-doping, which resulted in improvement of the efficiencies of the devices.

This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching f...

Perovskite-type CH3NH3(MA)PbI3−based photovoltaic devices were fabricated and characterized. Doping effects of cesium iodide (CsI), cesium bromide (CsBr) and tin bromide (SnBr2) on the photovoltaic properties and surface microstructures of the perovskite phase were investigated. Short-circuit current densities, open-circuit voltages and fill factors increased by CsI and SnBr2 addition. The surface coverage of the perovskite crystals was also improved by SnBr2 doping, which resulted in improvement of the fill factor. The cell prepared by a starting composition of MA0.95Cs0.05Pb0.95Sn0.05I2.90Br0.10 showed the best photovoltaic performance in the present work.