A systematic strategy for effectively engineering the charge extraction in inverted structured perovskite solar cells based on CH3NH3PbI3−xClxis provided. An optimized power conversion efficiency of 20.5% is realized.

Incorporation of appropriate amounts of Cs and Cl into the perovskite precursor could improve the stability of corresponding devices. A high power conversion efficiency of 20.31% without hysteresis is realized.

A humidity sensor made of uniform perovskite nanosheet arrays displayed good performance, and hence represents a new application for perovskite materials.

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Though various efforts on modification of electrodes are still undertaken to improve the efficiency of perovskite solar cells, attributing to the large scope of these methods, it is of significance to unveil the working principle systematically. Herein, inverted perovskite solar cells based on indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/CH NH PbI /phenyl-C61-butyric acid methyl ester (PC BM)/buffer metal/Al are constructed. Through the choice of different buffer metals to tune work function of the cathode, the contact nature of the active layer with the cathode could be manipulated well. In comparison with the device using Au/Al as the electrode that shows an unfavorable band bending for conducting the excited electrons to the cathode, the one with Ca/Al presents a dramatically improved efficiency over 17.1%, ascribed to the favorable band bending at the interface of the cathode with the active layer. Details for tuning the band bending and the corresponding charge transfer mechanism are given in a systematic manner. Thus, a general guideline for constructing perovskite photovoltaic devices efficiently is provided.

Each year, combustion at municipal solid waste incineration (MSWI) plants produces millions of tons of fly ash globally. This ash is characterized as a hazardous material and is mostly placed in landfills after a stabilization process or stored in hazardous waste sites. Thus, disposal of fly ash leaves a considerable social and environmental footprint and leads to high waste management costs. Thermochemical energy storage (TCES) systems are considered to be outstanding because of their high-energy density and near-zero energy loss over long periods of time. Calcium oxide (CaO), a main MSWI fly ash component, is a promising candidate for TCES. In this study, we investigate the potential of fly ash as a TCES material. To do so, we analyzed representative samples from different MSWIs using simultaneous thermal analysis (STA) under N2, CO2, and CO2/H2O atmospheres. These analyses were supported by additional techniques such as X-ray fluorescence (XRF) spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM). The STA results illustrate fly ash reactivity under different atmospheres. All samples could store heat through endothermic reactions and one sample was able to release stored heat under selected operating conditions. XRF analysis verified an average fly ash composition of 27% CaO, ICP-OES analysis demonstrated the presence of different heavy metals, and SEM analysis revealed the sintering and agglomeration of fly ash particles at high temperatures (1150 °C). This study shows that the use of fly ash as a TCES material is promising and that further investigation in the field is needed to corroborate this application.