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2D Ruddlesden–Popper perovskites are highly regarded materials for improving the stability of perovskite solar cells (PSCs). Wherein, self‐additive 2D perovskites have recently been proposed to provide substantial strategies for managing the crystallization kinetics and bulk defects. For a profound understanding of the formation mechanisms, herein, with selecting three self‐additive 2D perovskites as demonstrations, a comprehensive analysis of the self‐additive behavior combing experimental and theoretical calculations is conducted. Self‐additive 2D perovskites exhibit more suitable formation energies and strong interaction, which is conducive to realize the self‐additive effect to form more stable structure. As demonstrated, glycine (Gly)‐based spacer cations played a pivotal role in the nucleation and growth of 2D perovskites by adjusting the aggregation state of colloids precursor, resulting in excellent‐quality films with large average grain size (≈3 µm). Meanwhile, theoretical analysis of electronic distribution and binding energies (Eb) revealed that glycine ethyl ester (Gly‐E) perovskite possesses highly robust internal interactions, which will effectively mitigate defect formation and enhance device stability. Endowing with the above outstanding feature, Gly‐E devices exhibited an optimized PCE of 21.60%, one of the highest PCEs among all 2D RP PSCs (n ≤ 6). The findings provide a basis for the rational design of self‐additive 2D perovskites and achieving highly‐performance 2D RP PSCs. [ABSTRACT FROM AUTHOR]

High‐performance flexible photodetectors are urgently demanded for application in many emerging domains including flexible, wearable, portable, and stretchable optoelectronics. In this work, a highly efficient flexible photodetector made of a Ti3C2Tx MXene/pyramidal thin Si heterostructure is successfully fabricated. Thanks to the remarkable light trapping effect as confirmed by numerical modeling based on finite‐element method, the as‐constructed detector demonstrates excellent photoresponse performance in a broadband wavelength spectrum. The optimal responsivity, specific detectivity, and response speed reach ≈530 mA W−1, ≈1.21 × 1012 Jones and 30/14 µs, respectively, at zero bias under near‐infrared light illumination. Specifically, the responsivity is greatly enhanced by ≈2.65 times, as compared with a planar counterpart. In addition, the light detector can maintain its outstanding photoresponse properties upon 1000 cycles of bending test or at diverse bending radii of curvature, owing to its prominent mechanical flexibility and robust bending endurance. Finally, the capability of monitoring the heart rate of a person in a wideband wavelength spectrum and at various bending radii of curvature is presented. The above results imply the huge potential of the flexible light detector for use in some applications such as wearable health monitoring. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (SCs) have gained significant interest in various applications owing to their superior optoelectrical and physical characteristics as compared to polycrystalline films. However, a considerable portion of incident light is typically reflected at the surface of perovskite SCs, leading to insufficient light absorption within the crystal bulk, ultimately resulting in reduced performance of SC‐based photodetectors. In the present work, an inverted pyramid‐shaped structure is in situ introduced on the surface of an MAPbBr3 SC during the crystal growth process, which can reduce light reflection in the surface region and enhance light absorption of the SC. Additionally, the hydrophobic small molecule copper (II) phthalocyanine (CuPc) is thermally evaporated onto the SC, forming a CuPc/MAPbBr3 heterojunction for the first time. The CuPc/pyramid‐shaped MAPbBr3 heterojunction‐based photodetector exhibits self‐powered characteristics and superior optoelectrical performance, achieving a photocurrent of greater than 10−5 A (10−7 A), a responsiveness of 257 mA W−1 (8.84 mA W−1), and a detection rate of 2.98 × 1012 Jones (1.02 × 1011 Jones) at −2 V (0 V) bias. Simultaneously, the device demonstrates excellent long‐term stability under high humidity conditions, retaining 90.5% of its initial photocurrent even after 60 days in a 60–80% humidity environment. [ABSTRACT FROM AUTHOR]

Compared with polycrystalline films, perovskite single crystal is considered as a promising photoelectric material due to its unique advantages in quantum efficiency and carrier diffusion length. In this work, the micron-thickness MAPbBr3 single crystal was prepared through a highly repeatable process based on the crystal seed dissolution-growth method. A heterojunction of MAPbBr3/WO3 single crystal was realized through a simple thermal evaporation process, and the integrated C/MAPbBr3/WO3/C device demonstrated self-powered characteristics and high photoelectric performance, which showed good responsivity of about 111 mA/W, detectivity of 9.64×1011 Jones and fast response speed (0.11/0.56 ms). Meanwhile, the device exhibited good rectification performance (ratio of 125 at ±2 V) and reduced dark current due to the built-in electric field formed in the heterojunction. This study provides a facile, flexible, and highly repeatable method for the preparation of high-performance photodetectors based on MAPbBr3 single crystals with micrometer thickness. [ABSTRACT FROM AUTHOR]