Since its first report in 2009,CH_3NH_3PbI_3-based perovskite solar cells(PSCs)have emerged as one of the most exciting developments in the next generation photovoltaic(PV)technologies[1],with its PV conversion efficiency(PCE)rising spectacularly from3.81% to 22.1% in just 7 years.Such rapid advance is
Effective electron selective layer （ESL） is critical for the power conversion efficiency in organometal halide- based perovskite solar cells （PSCs）. In this work, a spincoating process has been developed to fabricate high quality nanocrystalline SnO2 film at 100℃ without further sintering at higher temperature. When used as ESL in PSCs, such SnO2 film shows greater electron extraction ability and higher efficiency than TiO2 film processed under similar condition, as evidenced by the efficient time-resolved photoluminescence （TRPL） quenching SnO2/CH3NH3PbI3 film. As a resuit, the SnO2-based PSCs possess higher open circuit voltage of 0.91 V, short circuit current density of 20.73 mA cm^-2, and fill factor of 64.25%, corresponding to a conversion efficiency of 12.10%, compared with 7.16% of TiO2-based PSCs. This demonstrates the great potential of applying spin-coating sintering-free process for the low-cost and large-scale manufacturing of PSCs.
Ternary Ⅰ–Ⅲ–Ⅵquantum dots（QDs） of chalcopyrite semiconductors exhibit excellent optical properties in solar cells. In this study, ternary chalcopyrite CuGaS2nanocrystals（2–5 nm） were one-pot anchored on TiO2nanoparticles（TiO2@CGS） without any long ligand. The solar cell with TiO2@CuGaS2/N719 has a power conversion efficiency of7.4%, which is 23% higher than that of monosensitized dye solar cell. Anchoring CuGaS2 QDs on semiconductor nanoparticles to form QDs/dye co-sensitized solar cells is a promising and feasible approach to enhance light absorption,charge carrier generation as well as to facilitate electron injection comparing to conventional mono-dye sensitized solar cells.
The energy band-gap and related factors of tantalum pentoxide with hexagonal phase were investigated using hybrid functional B3LYP and sX-LDA methods. The results showed that both sX-LDA and B3LYP techniques reveal the indirect semiconductor nature of δ-Ta2O5, whereas the obtained value of energy band-gap is much higher than previous theoretical reports but closer to the experimental data. The optical band- gap of δ-Ta2O5 is expected to originate from the O 2p→Ta 5d transition which may benefit from the d-s-p hybridization.
