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Advancing hole transport layers (HTL) to realize large‐area, flexible, and high‐performance perovskite solar cells (PSCs) is one of the most challenging issues for its commercialization. Here, a self‐assembled gradient Ti3C2Tx MXene incorporated PEDOT:PSS HTL is demonstrated to achieve high‐performance large‐area PSCs by establishing half‐caramelization‐based glucose‐induced MXene redistribution. Through this process, the Ti3C2Tx MXene nanosheets are spontaneously dispersed and redistributed at the top region of HTL to form the unique gradient distribution structure composed of MXene:Glucose:PEDOT:PSS (MG‐PEDOT). These results show that the MG‐PEDOT HTL not only offers favorable energy level alignment and efficient charge extraction, but also improves the film quality of perovskite layer featuring enlarged grain size, lower trap density, and longer carrier lifetime. Consequently, the power conversion efficiency (PCE) of the flexible device based on MG‐PEDOT HTL is increased by 36% compared to that of pristine PEDOT:PSS HTL. Meanwhile, the flexible perovskite solar minimodule (15 cm2 area) using MG‐PEDOT HTL achieve a PCE of 17.06%. The encapsulated modules show remarkable long‐term storage stability at 85 °C in ambient air (≈90% efficiency retention after 1200 h) and enhanced operational lifetime (≈90% efficiency retention after 200 h). This new approach shows a promising future of the self‐assembled HTLs for developing optoelectronic devices. [ABSTRACT FROM AUTHOR]

Driven by the Internet of Everything, one of the main goals in human–computer interaction is to achieve intuitive, effortless, and easy‐to‐learn communication. Thus, senseless optoelectronic devices with high response performance under ambient environment have an extensive application space in improving the interfacing between users and computers. Herein, a concept of wearable perovskite‐based shadow recognition sensor is demonstrated for ambient and nonobtrusive human–computer interaction. The multidimensional ordered nucleation and growth of perovskite crystals are promoted by introducing the self‐driving effect of liquid crystal (LC) oligomers. The resulted LC‐doped perovskite film (LC‐PVK) with micrometer‐sized grains can output relatively high photocurrent under indoor ambient light (≈500 lux). The LC‐based device exhibits over a hundred times of on–off ratio and fast response of millisecond level even after storage for more than 1200 h. The device also shows an ultratrace Pb2+ leakage of 1.02 μg L−1 in water, and still retains more than 90% of the photocurrent intensity after thousands of bending strains. Accordingly, a novel human–computer interaction is achieved by identifying external action commands with the recognition of shadows, which can provide a "haptic" perception for robots. [ABSTRACT FROM AUTHOR]

Perovskites as promising photovoltaic materials have been widely investigated due to their excellent photoelectric properties. Perovskite optoelectronic devices have been applied in fields of portable energy, light monitors, image sensors, etc. In recent years, wearable perovskite optoelectronic devices have been developed for their advantages of flexibility, stretchability, and light weight. In this review, the latest development of flexible and wearable perovskite optoelectronic devices is summarized. First, the preparation methods of optoelectronic devices are introduced, especially focusing on the large‐scale fabrication. Then the latest advances of various flexible devices are presented. In particular, the stability and safety of wearable devices, as well as the impact factors and corresponding solutions are discussed. Finally, the challenges for practical applications are put forward and discussed. [ABSTRACT FROM AUTHOR]

UV light always does great harm to perovskite solar cells, relentlessly degrading perovskites and shortening the lifetime of perovskite devices. Meanwhile, surface defects in perovskite films further accelerate the degradation process and serve as nonradiative charge recombination centers to deteriorate device efficiency. Herein, we demonstrate that a "sunscreen" molecule, 2‐hydroxy‐4‐methoxybenzophenone, not only protects the perovskite solar cell from UV degradation but also enables molecular defect passivation through interaction between functional groups and defects by molecular tautomerism under UV light illumination. Therefore, the sunscreen strategy efficiently enhances the UV endurance of PSCs and improves defect formation energy to −1.35 eV. The perovskite solar cell with sunscreen (sunscreen PSC) exhibits outstanding efficiencies of up to 23.09 % (0.04 cm2) and 19.73 % (1.00 cm2) as well as long‐term UV (UVa: 365 nm and UVb: 285 nm) stability. [ABSTRACT FROM AUTHOR]

A new crystal form of 1D perovskite (pyrrolidinium)PbI3 (orthorhombic phase) is synthesized and characterized. The 1D perovskite has a good film formability by solution spin coating and is in situ transformed to 3D CH3NH3PbI3 via the organic cation exchange approach in CH3NH2 atmosphere, which is dense and uniform. The converted 3D perovskite film is used as a light absorber, and the corresponding perovskite solar cell shows a power conversion efficiency of up to 19.2% under simulated 1 sun AM1.5G illumination (100 mW cm−2). [ABSTRACT FROM AUTHOR]

Extensive applications for photodetectors have led to demand for high‐responsivity polarization‐sensitive light detection. Inspired by the elaborate architecture of butterfly Papilio paris, a 1D nanograting bonded porous 2D photonic crystal perovskite photodetector (G‐PC‐PD) using a commercial DVD master and 2D crystalline colloidal arrays template was fabricated. The coupling effect from grating diffraction and reflection of the PC stopband renders the enhanced light harvesting of G‐PC‐PD. The porous scaffold and nanoimprinting process afford a highly crystalline perovskite film. White light responsivity and detectivity of G‐PC‐PD are up to 12.67 A W−1 and 3.22×1013 Jones (6∼7 times that of a pristine perovskite photodetector). The highly ordered nanograting arrays of G‐PC‐PD enable polarization‐sensitive light detection with a rate of −0.72 nA deg−1. This hierarchical perovskite integrated nanograting and 2D PC architecture opens a new avenue to high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Achieving light harvesting is crucial for the efficiency of the solar cell. Constructing optical structures often can benefit from micro‐nanophotonic imprinting. Here, a simple and facile strategy is developed to introduce a large area grating structure into the perovskite‐active layer of a solar cell by utilizing commercial optical discs (CD‐R and DVD‐R) and achieve high photovoltaic performance. The constructed diffraction grating on the perovskite active layer realizes nanophotonic light trapping by diffraction and effectively suppresses carrier recombination. Compared to the pristine perovskite solar cells (PSCs), the diffraction‐grating perovskite devices with DVD obtain higher power conversion efficiency and photocurrent density, which are improved from 16.71% and 21.67 mA cm−2 to 19.71% and 23.11 mA cm−2. Moreover, the stability of the PSCs with diffraction‐grating‐structured perovskite active layer is greatly enhanced. The method can boost photonics merge into the remarkable perovskite materials for various applications. [ABSTRACT FROM AUTHOR]

Perovskites, solar cells, tautomerism, UV stability Keywords: perovskites; solar cells; tautomerism; UV stability EN perovskites solar cells tautomerism UV stability 9144 9144 1 04/03/21 20210412 NES 210412 B UV light and surface defects b accelerate the degradation process of perovskite solar cells (PSCs). Back Cover: Tautomeric Molecule Acts as a "Sunscreen" for Metal Halide Perovskite Solar Cells (Angew. [Extracted from the article]

Perovskites, solar cells, tautomerism, UV stability Rücktitelbild: Tautomeric Molecule Acts as a "Sunscreen" for Metal Halide Perovskite Solar Cells (Angew. Keywords: perovskites; solar cells; tautomerism; UV stability EN perovskites solar cells tautomerism UV stability 9228 9228 1 04/03/21 20210412 NES 210412 B UV-Licht und Oberflächendefekte b beschleunigen den Degradationsprozess von Perowskit-Solarzellen (PSCs). [Extracted from the article]

Highlights from the article: Keywords: competitive growth; micro-contact print; perovskites; solar cells; surface wettability In article number 1900838, Mingzhu Li, Yanlin Song and co-workers report a competitive perovskite grain growth approach via a micro-contact print (MicroCP) method with CD discs as templates for printing a wettability-patterned substrate, to achieve a large-grained perovskite and avoid discontinuous perovskite films caused by the low wettability of substrates, resulting in efficiencies over 20% for the MicroCP perovskite solar cells. Competitive growth, micro-contact print, perovskites, solar cells, surface wettability.

Novel photovoltaic perovskite solar cells (PSCs) with high‐efficient photovoltaic property are largely in thrall to the uncertain perovskite grain size and inevitable defects. Here, inspired by the competitive growth between tree and grass in the forest system, a competitive perovskite grain growth approach via micro‐contact print (MicroCP) method (CD disk as templates) for printing wettability‐patterned substrate is proposed, aiming to achieve large‐grained perovskite and avoid discontinuous perovskite films caused by the low wettability of substrates. A MicroCP process is employed to construct a patterned wettability surface for the perovskite competitive growth mechanism on the electrode surface. This approach modifies the substrates quickly, ensures the uniform coverage of perovskite due to the function of ‐NH2 and Pb2+ bonds, and converts the perovskite films composed of small grains and pinholes into high‐quality perovskite films, free from pinholes and made up of large grains, resulting in efficiencies over 20% for the MicroCP PSCs. [ABSTRACT FROM AUTHOR]