ZKC

A highly flexible perovskite film prepared by incorporating elastomer polyurethane (PU) is described by Licheng Tan, Yiwang Chen, and co-workers in article number 1703061. By cross-linking the grain boundaries between neighboring perovskite crystals, a PU network is formed to significantly improve the bendability of perovskite films. This strategy is expected to be of profound significance for the realization of perovskite solar cells as flexible and wearable devices.

The pervasive use of non-scalable fabrication methods in research greatly hinders the translation to industrial manufacturing of perovskite and organic solar cells. Inkjet printing is a scalable technique suitable for lab to industrial scale production. In article number 1703704, Dechan Angmo and co-workers comprehensively review inkjet printing application in the fabrication of different functional layers in organic and perovskite solar cells.

Inherent poor stability of perovskite nanocrystals (NCs) is the main impediment preventing broad applications of the materials. Here, TiO₂ shell coated CsPbBr₃ core/shell NCs are synthesized through the encapsulation of colloidal CsPbBr₃ NCs with titanium precursor, followed by calcination at 300 °C. The nearly monodispersed CsPbBr₃/TiO₂ core/shell NCs show excellent water stability for at least three months with the size, structure, morphology, and optical properties remaining identical, which represent the most water-stable inorganic shell passivated perovskite NCs reported to date. In addition, TiO₂ shell coating can effectively suppress anion exchange and photodegradation, therefore dramatically improving the chemical stability and photostability of the core CsPbBr₃ NCs. More importantly, photoluminescence and (photo)electrochemical characterizations exhibit increased charge separation efficiency due to the electrical conductivity of the TiO₂ shell, hence leading to an improved photoelectric activity in water. This study opens new possibilities for optoelectronic and photocatalytic applications of perovskites-based NCs in aqueous phase.

TiO₂ shell coated CsPbBr₃ core/shell nanocrystals are successfully constructed, resulting in excellent water, photo and thermal stability. TiO₂ shell coating effectively increases charge separation efficiency, hence leading to an improved photoelectric activity in water.

Inspired by the remarkable promotion of power conversion efficiency (PCE), commercial applications of organic photovoltaics (OPVs) can be foreseen in near future. One of the most promising applications is semitransparent (ST) solar cells that can be utilized in value-added applications such as energy-harvesting windows. However, the single-junction STOPVs utilizing fullerene acceptors show relatively low PCEs of 4%–6% due to the limited sunlight absorption because it is a dilemma that more photons need to be harvested in UV–vis–near-infrared (NIR) region to generate high photocurrent, which leads to the significant reduction of device transparency. This study describes the development of a new small-bandgap electron-acceptor material ATT-2, which shows a strong NIR absorption between 600 and 940 nm with an E_g^opt of 1.32 eV. By combining with PTB7-Th, the as-cast OPVs yield PCEs of up to 9.58% with a fill factor of 0.63, an open-circuit voltage of 0.73 V, and a very high short-circuit current of 20.75 mA cm⁻². Owing to the favorable complementary absorption of low-bangap PTB7-Th and small-bandgap ATT-2 in NIR region, the proof-of-concept STOPVs show the highest PCE of 7.7% so far reported for single-junction STOPVs with a high transparency of 37%.

A small-bandgap electron acceptor, ATT-2, is designed and synthesized. By combining PTB7-Th donor, the power conversion efficiencies reach 9.58% and 7.74% for opaque and semitransparent devices, respectively. The highest PCE among single-junction STOPVs can be attributed to the beneficial complementary near-infrared absorption of the low-bandgap donor and small-bandgap acceptor. Non-fullerene acceptors are thus very promising for the development of high-performance STOPVs.

Large-scale and highly ordered 3D perov­skite nanowire (NW) arrays are achieved in nanoengineering templates by a unique vapor–solid–solid reaction process. The excellent material properties, in conjunction with the high integration density of the NW arrays, make them promising for 3D integrated nanoelectronics/optoelectronics. Image sensors with 1024 pixels are assembled and characterized to demonstrate the technological potency.

On page 6371, W. Zhou, P. A. Hu, and co-workers report a novel approach for growing stable p-type MoS₂ atomic layers in large scale by using Mo-containing sol-gel, including 1% tungsten (W). The small tungsten oxide clusters contribute to the p-type behavior. Availability of regular arrays with different shapes via soft-lithography techniques holds great promise for highly integrated electronics and flexible device applications.