High-Efficiency Carbon-based CsPbI2 Br Perovskite Solar Cells from Dual Direction Thermal Diffusion Treatment with Cadmium Halides.

In recent years, carbon-based CsPbI2 Br perovskite solar cells (PSCs) have attracted more attention due to their low cost and good stability. However, the power conversion efficiency (PCE) of carbon-based CsPbI2 Br PSCs is still no more than 16%, because of the defects in CsPbI2 Br or at the interface with the electron transport layer (ETL), as well as the energy level mismatch, which lead to the loss of energy, thus limiting PCE values. Herein, a series of cadmium halides are introduced, including CdCl2 , CdBr2 and CdI2 for dual direction thermal diffusion treatment. Some Cd2+ ions thermally diffuse downward to passivate the defects inside or on the surface of SnO2 ETL. Meanwhile, the energy level structure of SnO2 ETL is adjusted, which is in favor of the transfer of electron carriers and blocking holes. On the other hand, part of Cd2+ and Cl- ions thermally diffuse upward into the CsPbI2 Br lattice to passivate crystal defects. Through dual direction thermal diffusion treatment by CdCl2 , CdI2 and CdBr2 , the performance of devices has been significantly improved, and their PCE has been increased from 13.01% of the original device to 14.47%, 14.31%, and 13.46%, respectively. According to existing reports, 14.47% is one of the highest PCE of carbon-based CsPbI2 Br PSCs with SnO2 ETLs.

Highly Efficient CsPbBr3 Planar Perovskite Solar Cells via Additive Engineering with NH4SCN.

Improving stability is a major aspect for commercial application of perovskite solar cells (PSCs). The all-inorganic CsPbBr3 perovskite material has been proven to have excellent stability. However, the CsPbBr3 film has a small range of light absorption and serious charge recombination at the interface or inside the device, so the power conversion efficiency is still lower than that of the organic-inorganic hybrid one. Here, we successfully fabricate high-quality CsPbBr3 films via additive engineering with NH4SCN. By incorporating NH4+ and pseudo-halide ion SCN- into the precursor solution, a smooth and dense CsPbBr3 film with good crystallinity and low trap state density can be obtained. At the same time, the results of a series of photoluminescence and electrochemical analyses including electrical impedance spectroscopy, space-charge limited current method, Mott-Schottky data, and so on reveal that the NH4SCN additive can greatly reduce the trap state density of the CsPbBr3 film and also effectively inhibit interface recombination and promote charge transport in the CsPbBr3 planar PSC. Finally, the CsPbBr3 planar PSC prepared with a molar ratio of 1.5% NH4SCN achieves a champion efficiency of 8.47%, higher than that of the pure one (7.12%).

Dimericursones A and B: two unprecedented hexacyclic dimeric diterpenoids from the root barks of Jatropha curcas.

Dimericursones A and B (1 and 2), two unprecedented hexacyclic dimeric diterpenoids, were obtained from the root barks of Jatropha curcas. Their structures were elucidated by extensive spectroscopic analysis, electronic circular dichroism calculations, and single-crystal X-ray diffraction. Dimericursone B (2) showed significant inhibition on nitric oxide production of lipopolysaccharide-induced RAW264.7 macrophages with IC50 values of 5.65 µM.