Thermally unstable nature of hybrid organic-inorganic perovskites has been a major obstacle to fabricating the long-term operational device. A cesium lead halide perovskite has been suggested as an alternative light absorber, due to its superb thermal stability. However, the phase instability and poor performance are hindering the further progress. Here, cesium lead halide perovskite solar cells with enhanced performance and stability are demonstrated via incorporating potassium cations. Based on CsKPbIBr, the planar-architecture device achieves a power conversion efficiency of 10.0%, which is a remarkable record in the field of inorganic perovskite solar cells. In addition, the device shows an extended operational lifetime against air. Our research will stimulate the development of cesium lead halide perovskite materials for next-generation photovoltaics.

Recently, polymer−fullerene based bulk heterojunction (BHJ) solar cells, which contain blends of poly ({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl}) (PTB7) and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM), have been widely studied due to exhibiting high power conversion efficiency (PCE) and well-defined nanomorphology. Because of the short exciton diffusion pathway (less than 10 nm) in organic thin films, the optimization of PTB7:PC 71 BM BHJ with optimized morphology is very important between the donor and acceptor. In order to increase nanoscale phase separation, the chemical additives of 1,8-diiodooctane (DIO) have been used in PTB7:PC 71 BM blend systems. However, the mechanism studies of DIO in BHJ solar cells and its effectiveness on device stability are unclear. In this study, we fabricated polymer solar cells (PSCs) based on PTB7:PC 71 BM BHJ with various DIO concentrations to investigate not only correlation between device performances and different morphologies, but also the influence of additives on device stabilities. Positive effects of DIO, which were induced by efficient charge separation in BHJ at optimized blending ratio, are proved by the results of time-resolved photoluminescence (TRPL), and negative effects of DIO on a device stability have been investigated according to the ISOS-D-1 protocol.

A general methodology is reported to create organic–inorganic hybrid metal halide perovskite films with enlarged and preferred‐orientation grains. Simply pressing polyurethane stamps with hexagonal nanodot arrays on partially dried perovskite intermediate films can cause pressure‐induced perovskite crystallization. This pressure‐induced crystallization allows to prepare highly efficient perovskite solar cells (PSCs) because the preferred‐orientation and enlarged grains with low‐angle grain boundaries in the perovskite films exhibit suppressed nonradiative recombination. Consequently, the photovoltaic response is dramatically improved by the uniaxial compression in both inverted‐planar PSCs and normal PSCs, leading to power conversion efficiencies of 19.16%.

Metallic nanoparticles (NPs) exhibit a localized surface plasmon resonance (LSPR) and act as scattering centers and subwavelength antennas, so metallic NPs can be incorporated into perovskite solar cells (PSCs) to effectively improve the light absorption of light harvesting devices. Here, we have embedded Au nanoparticles (NPs) into the hole transport layer (HTL) of the PSCs to investigate the photovoltaic effect of the PSCs with Au NPs. Interestingly, it was found that Au NPs dispersed spiro-OMeTAD HTL solution could naturally end up located near the perovskite layer as the result of the spin-coating step. Solar cell performance observations indicate that the LSPR and electrical effects of Au NPs enhance the photovoltaic response of PSCs, in spite of a slight decrease in the open-circuit voltage (VOC), by causing an incredible improvement in the photocurrent density as a dominant factor.

A 2H-MoS2 (H=hexagonal) ultrathin nanomesh with high defect generation and large porosity is demonstrated to improving electrochemical performance, including in lithium-ion batteries (LIBs) and the hydrogen evolution reaction (HER), with the aid of a 3D reduced graphene oxide (RGO) scaffold as fast electron and ion channels. The 3D defect-rich MoS2 nanomesh/RGO foam (Dr-MoS2 Nm/RGO) can be easily obtained through a one-pot cobalt acetate/graphene oxide (GO) co-assisted hydrothermal reaction, in which GO, cobalt and acetate ions are co-morphology-controlling agents and defect inducers. As an anode material for LIBs, Dr-MoS2 Nm/RGO has only a 9% capacity decay at a 10 C discharge rate versus 0.2 C with stable cyclability at the optimized composition (5 wt% RGO to MoS2 and 2 mol% Co to Mo), and significantly achieves 810 mA h g(-1) at a high current density of 9.46 A g(-1) over at least 150 cycles. Moreover, Dr-MoS2 Nm/RGO exhibits superior activity for the HER with an overpotential as low as 80 mV and a Tafel slope of about 36 mV per decade. In contrast to the MoS2 nanosheet/RGO (MoS2 Ns/RGO), which is synthesized in the absence of cobalt ions, Dr-MoS2 Nm/RGO provides high interconnectivity for efficient lithium-ion transport, and rich defects as electrochemically active sites. DFT is used to prove the existence of rich defects due to anion replacement to become a Co-Mo-S atomic structure, releasing inert basal planes to active sites.

The p/n junction of MoS2/N-RGO co-catalysts not only works as the HER and OER electrocatalyst for H2 and O2 generation respectively, but also facilitates charge separation by its inner electric field.

A stepwise four‐electron reaction significantly alleviates the thermodynamics reaction barrier for overall water splitting. Regenerated 1D carbon nitride nanowire bundles from tailoring and reassembly of 2D g‐C3N4 produce novel physicochemical and optoelectronic properties, which well realize the stepwise four‐electron reaction along with a quantum efficiency of 5.2‰ at 420 nm.

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