Heng Liu

Abstract Low temperature solution processed planar‐structure perovskite solar cells gain great attention recently, while their power conversions are still lower than that of high temperature mesoporous counterpart. Previous reports are mainly focused on perovskite morphology control and interface engineering to improve performance. Here, this study systematically investigates the effect of precise stoichiometry, especially the PbI 2 contents on device performance including efficiency, hysteresis and stability. This study finds that a moderate residual of PbI 2 can deliver stable and high efficiency of solar cells without hysteresis, while too much residual PbI 2 will lead to serious hysteresis and poor transit stability. Solar cells with the efficiencies of 21.6% in small size (0.0737 cm 2 ) and 20.1% in large size (1 cm 2 ) with moderate residual PbI 2 in perovskite layer are obtained. The certificated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar‐structure perovskite solar cells, showing the planar‐structure perovskite solar cells are very promising.

Abstract The photocurrent generation in photovoltaics relies essentially on the interface of p-n junction or Schottky barrier with the photoelectric efficiency constrained by the Shockley-Queisser limit. The recent progress has shown a promising route to surpass this limit via the bulk photovoltaic effect for crystals without inversion symmetry. Here we report the bulk photovoltaic effect in two-dimensional ferroelectric CuInP 2 S 6 with enhanced photocurrent density by two orders of magnitude higher than conventional bulk ferroelectric perovskite oxides. The bulk photovoltaic effect is inherently associated to the room-temperature polar ordering in two-dimensional CuInP 2 S 6 . We also demonstrate a crossover from two-dimensional to three-dimensional bulk photovoltaic effect with the observation of a dramatic decrease in photocurrent density when the thickness of the two-dimensional material exceeds the free path length at around 40 nm. This work spotlights the potential application of ultrathin two-dimensional ferroelectric materials for the third-generation photovoltaic cells.

under DUV light illumination at 212 nm and a cutoff wavelength at around 225 nm. This work demonstrates that two-dimensional h-BN layers are promising for the construction of high-performance solar-blind photodetectors.

With the continuous emission of greenhouse gases, the rational transformation and utilization of CO2 is particularly important. Cyclic carbonates are a kind of versatile compounds and have wide applications in Li-ion batteries, pharmaceutical manufacturing and many fine chemicals. Cycloaddition of CO2 and epoxide to synthesize cyclic carbonates is considered one of the most promising CO2 conversion routes because of its 100% atomic economy, non-toxicity, as well as a more economic technical route for the utilization of CO2. In this paper, this review surveys the synthesis of cyclic carbonates employing CO2 as a building block. The mechanisms of CO2 activation have been described in detail due to the thermodynamic stability of CO2 molecule. The reaction mechanism of CO2 and epoxide is expounded, and seven CO2 activation methods are summarized and compared, deeply analyzing the research progress of recent years. To reduce the activation energy of the CO2 conversion, the utilization of catalysts is very crucial. Various types of catalysts suitable for the synthesis of cyclic carbonates derived from CO2 have been expounded in depth. Finally, the development trend of catalysts is prospected. The development of improved catalysts is strongly demanded for successful commercialization of CO2 transformation technologies. This review enables researchers to timely seize the current advancements and thus may provide some rewarding insights for future investigations on the synthesis of cyclic carbonates employing CO2 as the feedstock. It will provide a good reference and guide for scholars to achieve the better improvements.