Environmental regulation and corporate tax avoidance-Evidence from China.

In this study, we used a difference-in-difference (DID) approach to analyze the effect of environmental regulation on corporate tax avoidance behavior based on China's carbon emissions trading pilot policy of 2013. Our findings were as follows: (1) Environmental regulation has led companies to adopt further tax evasion behaviors. Furthermore, the core conclusion was confirmed after a series of robust and endogenous tests, such as parallel trends and PSM-DID (propensity score matching-difference-in-difference). (2) Environmental regulations increase tax avoidance activities by reducing corporate cash flows. (3) The influence of environmental regulation on firm tax evasion is highly pronounced among non-state-owned enterprises, big-scale enterprises, and enterprises with a high degree of industry competition.

Excess Cesium Iodide Induces Spinodal Decomposition of CsPbI2Br Perovskite Films.

We report an exploratory study on the crystal formation behavior of CsPbI2Br perovskite films by adding excess cesium iodide (CsI). Surprisingly, facile co-crystallization of CsI and CsPbI2Br in the form of spinodal decomposition is observed. Significantly, the two phases spontaneously form morphing into a remarkably uniform bicontinuous nanoscale blend with high orientational correlation through the well-matched (110) plane of CsI and the (200) plane of CsPbI2Br. The CsPbI2Br films produced by the spinodal decomposition method not only enjoy a compact surface, low defect concentration, and long carrier lifetimes, they also retain their excellent charge transport property. By employing such a CsPbI2Br film for carbon-based perovskite solar cells, power conversion efficiency exceeding 10% is achieved with remarkable thermal stability. Our results provide valuable insight into the role of CsI in perovskite crystallization and a promising approach for designing inorganic halide perovskite-based devices.

Boron Doping of Multiwalled Carbon Nanotubes Significantly Enhances Hole Extraction in Carbon-Based Perovskite Solar Cells.

Compared to the conventional perovskite solar cells (PSCs) containing hole-transport materials (HTM), carbon materials based HTM-free PSCs (C-PSCs) have often suffered from inferior power conversion efficiencies (PCEs) arising at least partially from the inefficient hole extraction at the perovskite-carbon interface. Here, we show that boron (B) doping of multiwalled carbon nanotubes (B-MWNTs) electrodes are superior in enabling enhanced hole extraction and transport by increasing work function, carrier concentration, and conductivity of MWNTs. The C-PSCs prepared using the B-MWNTs as the counter electrodes to extract and transport hole carriers have achieved remarkably higher performances than that with the undoped MWNTs, with the resulting PCE being considerably improved from 10.70% (average of 9.58%) to 14.60% (average of 13.70%). Significantly, these cells show negligible hysteretic behavior. Moreover, by coating a thin layer of insulating aluminum oxide (Al2O3) on the mesoporous TiO2 film as a physical barrier to substantially reduce the charge losses, the PCE has been further pushed to 15.23% (average 14.20%). Finally, the impressive durability and stability of the prepared C-PSCs were also testified under various conditions, including long-term air exposure, heat treatment, and high humidity.

Colloidal Precursor-Induced Growth of Ultra-Even CH3NH3PbI3 for High-Performance Paintable Carbon-Based Perovskite Solar Cells.

Carbon-based hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted intense attention due to their relatively high stability. However, their power conversion efficiency (PCE) is still low, especially for the simplest paintable carbon-based PSCs (C-PSCs), whose performance is greatly limited by poor contact at the perovskite/carbon interface. To enhance interface contact, it is important to fabricate an even-surface perovskite layer in a porous scaffold, which is not usually feasible due to roughness of the crystal precursor. Herein, colloidal engineering is applied to replace the traditional crystal precursor with a colloidal precursor, in which a small amount of dimethyl sulfoxide (DMSO) is added into the conventional PbI2 dimethylformamide (DMF) solution. After deposition, PbI2(DMSO) adduct colloids (which are approximately tens of nanometers in size) are stabilized and dispersed in DMF to form a colloidal film. Compared with PbI2 and PbI2(DMSO) adduct crystal precursors deposited from pure DMF and DMSO solvents, respectively, the PbI2(DMSO) adduct colloidal precursor is highly mobile and flexible, allowing an ultra-even surface to be obtained in a TiO2 porous scaffold. Furthermore, this ultra-even surface is well-maintained after chemical conversion to CH3NH3PbI3 in a CH3NH3I solution. As a result, the contact at the CH3NH3PbI3/carbon interface is significantly enhanced, which largely boosts the fill factor and PCE of C-PSCs. Impressively, the achieved champion PCE of 14.58% is among the highest reported for C-PSCs.

Patterned growth of luminescent metal-organic framework films: a versatile electrochemically-assisted microwave deposition method.

Electrochemically-assisted microwave deposition technology, a facile method for the fabrication of luminescent metal-organic framework (LMOF) films, is presented herein. This method was further developed into a versatile method for preparing patterned LMOF films. The strategy based on this method can spatially locate microcrystals of MOFs on a surface, which provides great promise in anti-counterfeiting barcode applications.

One-pot colloidal chemistry route to homogeneous and doped colloidosomes.

Colloidosomes are usually produced from a series of building blocks with different sizes ranging from several nanometers to micrometers or various shapes, such as particles, microrods, and quantum dots. Colloidosomes can possess a variety of characteristics in terms of photics, electrology, mechanical strength, and selective permeability, derived from their building blocks. However, poor mechanical stability and complicated synthesis processes have limited the applications of colloidosomes. Here, we report a new one-pot colloidal chemistry route to synthesize phenol formaldehyde resin (PFR), Ag@PFR, and Au@PFR colloidosomes with high yields. The method can be modified to synthesize different kinds of doped colloidosomes with different components, which will provide a new approach to design colloidosomes with different functions.