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Wide‐bandgap (WBG) perovskite solar cells (PSCs) have garnered significant attention for their potential applications in tandem solar cells. However, their large open‐circuit voltage (VOC) deficit and serious photo‐induced halide segregation remain the main challenges that impede their applications. Herein, a post‐treatment strategy without thermal annealing is presented to form a 2D top layer of 2‐thiopheneethylammonium lead halide (n = 1) on WBG perovskites. This thermal annealing‐free post‐treatment method can more effectively passivate the defects of WBG methylamine (MA)‐free formamidinium/cesium lead iodide/bromide perovskite films and suppress photo‐induced perovskite phase segregation, as compared with the thermal annealing method that yields multi‐2D phases. The resulting opaque and semi‐transparent 1.66 eV‐bandgap perovskite solar cells deliver maximum power conversion efficiencies of 21.47% (a small VOC deficit of 0.43 V) and 19.11%, respectively, both of which are among the highest reports for inverted MA‐free WBG PSCs. Consequently, four‐terminal all‐perovskite tandem cells realize a remarkable efficiency of 26.64%, showing great promise for their applications in efficient multi‐junction tandem solar cells. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (quasi‐2D) perovskite light‐emitting diodes (PeLEDs) are considered as one of the most potential candidates in electroluminescence territory owing to their unique quantum confinement effect and excellent thermal stability of the light. Nevertheless, heterogeneous energy domain distribution leads to severe non‐radiative recombination in the process of energy transfer, which enormously hinders the performance and application of PeLEDs. Herein, an ambipolar amino acid, 5‐aminovaleric acid (5AVA), is demonstrated to be able to coordinate lead and halides simultaneously with its carboxyl and amidogen groups. The coordinated ambipolar molecule not only reconstitutes energy domains of perovskites but also minimizes the interfacial defects of PeLEDs. Accordingly, the presence of 5AVA in perovskite precursors leads to dramatic suppression of the n = 1 and n = 2 phases and accelerates energy transfer from wide bandgap domains to narrow bandgap ones. As a result, maximum external quantum efficiency (EQE) of 19.3% (18.20% ± 1.10%) is achieved in quasi‐2D green PeLEDs with current efficiency of 61.7 cd A−1. [ABSTRACT FROM AUTHOR]

External encapsulation technique as a straightforward craft process has been adopted to prevent the infiltration of moisture and oxygen, thereby improving environmental stabilities of lead halide perovskite solar cells (PSCs). However, irreversible light‐induced degradation originating from various vacancies and ion diffusion or migration inside the device cannot be efficiently solved by external encapsulation. Herein, an internal encapsulation strategy by introducing NbCl5 at the buried tin oxide/perovskite interface and spin‐casting n‐butylammonium bromide on top of perovskite is developed to comprehensively passivate the vacancies and hence block the channels for ion diffusion or migration. The internal encapsulation strategy results in better homogeneous electron transport layer and effective vacancy passivation at the buried interface and simultaneously generates a more homogeneous, better crystallized perovskite in the vertical direction with significantly reduced residual PbI2. Furthermore, fewer oxygen vacancies and formation of ultrathin Nb2O5 lead to a better interfacial energy level alignment for electron transfer. As a result, power conversion efficiency (PCE) of the resulting PSCs is as high as 24.01%. More importantly, the device demonstrates an excellent stability, retaining 88% of its initial PCE at its maximum power point tracking measurement (under 100 mW cm–2 white light illumination at ≈55 °C temperature, in N2 atmosphere) after 1000 h. [ABSTRACT FROM AUTHOR]

P‐type semiconductor cuprous oxide (Cu2O) offers promising optoelectronic applications such as solar cells and photodetectors owing to its considerable absorption coefficients and high carrier mobility. However, polycrystalline Cu2O films with low carrier mobility resulting from excessive grain boundaries and structure disorder fail to meet the demands for these optoelectronic applications. Here a stress‐assisted thermal oxidation method to fabricate p‐type <110>‐textured quasi‐single crystalline Cu2O (c‐Cu2O) wafers with centimeter‐scale grains is developed. It is found that strain energy induced by thermal contact stress plays a critical role in crystal growth. The resultant <110>‐textured quasi‐single c‐Cu2O wafers exhibit excellent crystallinity with rocking curve having a low full width at half maximum of 0.022°, a low defect density of 2 × 1011 cm−3, a high mobility exceeding 100 cm2 V−1 s−1, and a long minority lifetime of 98.5 µs. Such quasi‐single c‐Cu2O wafers lead to efficient solar cells with an open‐circuit voltage of 0.95 V and highly responsive photodetectors with superior cycling stability. These results indicate not only the advancement of fabricating high‐quality Cu2O wafers upon controllable methodology but also the promising optoelectronic applications using p‐type metal oxide semiconductors. [ABSTRACT FROM AUTHOR]

Trap‐induced nonradiative recombination and decomposition are the major limiting factors that hinder the development of mixed‐halide wide‐bandgap perovskite solar cells. Specifically, the incorporation of formamidinium (FA+) and bromide in wide‐bandgap (WBG) perovskite materials leads to shallow‐energy‐level traps and inferior light stability. Herein, the electron‐withdrawing molecule 2,3,5,6 tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) is used as an effective passivator and stabilizer, which has molecular interaction with the FA+ cation for reducing trap densities and enhancing the stability of WBG perovskite solar cells. It is found that the extended π aromatic system in F4‐TCNQ can enhance the binding energy and stabilize the FA+ cation in perovskite films. Furthermore, the 1.67 eV bandgap inverted perovskite solar cells with a small amount of F4‐TCNQ have shallower defect levels, reduced trap density, and decreased nonradiative recombination, therefore giving a remarkably improved power conversion efficiency (PCE) of 20.0%. Most importantly, the unencapsulated devices with F4‐TCNQ additive have greatly enhanced stability, maintaining 88% of their peak PCEs under continuous illumination after 840 h, whereas the control devices only retain 48% of their PCEs after 500 h. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (NCs) serve as a kind of ideal semiconductor for luminescence and display applications. However, the optoelectronic performance and stability of perovskite NCs are mainly subjected to current ligand strategies since these ligands exhibit a highly dynamic binding state, which complicates NC purification and storage. Herein, a method named diffusion‐induced extraction is developed for crystallization (DEC) at room temperature, in which silicone oil serves as a medium to separate the solvent from perovskite precursors and diethyl ether promotes the nucleation, leading to highly emissive perovskite NCs. The formation mechanism of NCs using this approach is elucidated, and their optoelectronic properties are fully characterized. The resultant NCs ink exhibits a high photoluminescence quantum yield (PLQY) over 90% with a narrow full width at half maximum of 17 nm. The DEC method strengthens the interaction between ligand and NCs via the hydrophobic silicone oil. Therefore, the NCs maintain almost 95% of their initial PLQYs after aging more than seven months in air. The findings will be of great significance for the continued advancement of high PLQY perovskite NCs through a better understanding of formation dynamics. The DEC strategy presents a major step forward for advancing the field of perovskite semiconductor nanomaterials. [ABSTRACT FROM AUTHOR]

The article focuses on the stratigraphic analysis of the Ordovician period where the level of the greenhouse gases was at it's highest level.

Mixed tin–lead (Sn–Pb) perovskites often face a daunting challenge: rapid and uncontrollable crystallization, leading to a plethora of defects and significant stress. This issue is particularly exacerbated during the blade‐coating preparation of scalable Sn–Pb perovskite films. In this study, a facile strategy involving the addition of ammonium citrate (AC) to narrow‐bandgap mixed Sn–Pb perovskite precursors is introduced. AC, armed with its arsenal of multiple carboxyl and amino groups, acts as a virtuoso conductor, orchestrating controlled crystal growth by harmonizing with Pb2+ and Sn2+ ions. This addition significantly boosts the crystallinity of the perovskite films, alleviates interface stress, inhibits Sn2+ oxidation, and mitigates interfacial defects. Consequently, The blade‐coated AC‐incorporated mixed Sn–Pb perovskite solar cells achieve a high photovoltaic conversion efficiency of nearly 21%. Furthermore, extending this strategy to two‐terminal all‐perovskite tandem solar cells yielded a remarkable maximum efficiency of 27.20%. This work presents an effective strategy for producing efficient blade‐coated mixed Sn–Pb perovskite solar cells, heralding a pathway toward scalable fabrication of all‐perovskite tandem solar cells. [ABSTRACT FROM AUTHOR]