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Organic-inorganic methylammonium lead iodide perovskite (MAPbI3) nanowires (NWs) have attracted significant attention in the realm of optoelectronic devices due to their outstanding optoelectronic properties. However, the persistent challenge of high trap densities has been a limiting factor in realizing their full potential in device performance. To address this challenge, we incorporated cesium (Cs) and systematically investigated the impact of Cs concentration on the trap densities and the optoelectronic characteristics of Cs x MA(1− x)PbI3 NWs. Our findings unveiled an initial reduction in trap densities as Cs+ content increased, with the lowest point occurring at x = 0.2. However, beyond this threshold, trap densities began to rise, eventually surpassing those observed in pure MAPbI3 at x = 0.4. Furthermore, we fabricated single NW photodetectors to assess how Cs+ content influenced optoelectronic properties. The results indicated that Cs+ incorporation led to enhancements in photocurrent and response speed, withthe optimal performance observed at x = 0.2. Our study provides valuable insights into the role of Cs+ incorporation in tailoring the optoelectronic properties of perovskite NWs. [ABSTRACT FROM AUTHOR]

Organic—inorganic hybrid perovskites have attracted considerable attention for developing novel optoelectronic devices owing to their excellent photoresponses. However, conventional nanolithography of hybrid perovskites remains a challenge because they undergo severe damage in standard lithographic solvents, which prohibits device miniaturization and integration. In this study, a novel transparent stencil nanolithography (t‐SL) technique is developed based on focused ion beam (FIB)‐assisted polyethylene terephthalate (PET) direct patterning. The proposed t‐SL enables ultrahigh lithography resolution down to 100 nm and accurate stencil mask alignment. Moreover, the stencil mask can be reused more than ten times, which is cost‐effective for device fabrication. By applying this lithographic technique to hybrid perovskites, a high‐performance 2D hybrid perovskite heterostructure photodetector is fabricated. The responsivity and detectivity of the proposed heterostructure photodetector can reach up to 28.3 A W−1 and 1.5 × 1013 Jones, respectively. This t‐SL nanolithography technique based on FIB‐assisted PET direct patterning can effectively support the miniaturization and integration of hybrid‐perovskite‐based electronic devices. [ABSTRACT FROM AUTHOR]

The bottom‐up preparation of two‐dimensional material micro‐nano structures at scale facilitates the realisation of integrated applications in optoelectronic devices. Fibrous Phosphorus (FP), an allotrope of black phosphorus (BP), is one of the most promising candidate materials in the field of optoelectronics with its unique crystal structure and properties.[1] However, to date, there are no bottom‐up micro‐nano structure preparation methods for crystalline phosphorus allotropes.[1c, 2] Herein, we present the bottom‐up preparation of fibrous phosphorus micropillar (FP‐MP) arrays via a low‐pressure gas‐phase transport (LP‐CVT) method that controls the directional phase transition from amorphous red phosphorus (ARP) to FP. In addition, self‐powered photodetectors (PD) of FP‐MP arrays with pyro‐phototronic effects achieved detection beyond the band gap limit. Our results provide a new approach for bottom‐up preparation of other crystalline allotropes of phosphorus. [ABSTRACT FROM AUTHOR]

Nanowires (NWs)-based heterojunction photodetectors (PDs) have been widely applied in the fields of remote sensing, night vision, environmental monitoring, and optical communications with high light absorption coefficient and photoelectric conversion efficiency. Here, S-GaAs NWs/Si heterojunction was developed to form a broadband self-powered PDs by growing GaAs NWs on Si substrate through the sulfur-catalyzed assisted chemical vapor deposition (CVD) technology. Compared with the pure GaAs NWs, the sulfur-assisted catalysts could not only inhibit Ostwald ripening of Au seeds to improve the crystalline quality of NWs but also form a thin Ga–S bond passivation layer to reduce surface defects and enhance the optoelectronic performance of the PDs. The fabricated GaAs NWs/Si heterojunction PDs exhibit excellent performances with the large responsivity of 10.3 mA W−1 and high detectivity of 9.59 × 1012 cm Hz1/2 W−1. Additionally, the designed PDs have the broadband wavelength photoresponse from visible to near infrared and fast response speed (rise/fall time of 3.8/21.8 ms). Importantly, the develop strategy of hybrid heterojunction PDs can be extended to other semiconductor materials for facilitating the practical application of high-performance optoelectronic devices. • Facile sulfur-assisted strategy to construct GaAs nanowires/Si heterojunctions for broadband self-powered photodetectors. • GaAs nanowires/Si photodetector exhibits excellent an impressive responsivity of 10.3 mA W−1 and high detectivity of up to 9.59 × 1012 Jones. • GaAs nanowires/Si photodetector demonstrates fast rise/fall times of 3.8/21.8 ms and long-term stability. [ABSTRACT FROM AUTHOR]

Black phosphorus (BP) is an emerging two-dimensional semiconductor material, which has interesting structural features and broad application prospects in the fields of optoelectronic devices, energy storage, and biomedicine. However, a large amount of evidence is still needed to clarify the potential mechanism for the synthesis of high-quality BP crystals in chemical vapor transport (CVT) reactions. In this work, high-purity BP crystals were synthesized by the CVT method in an amorphous red phosphorus (aRP), Sn and I2 system. We found that the synthesis of BP experienced the three stage structural transformation of aRP–P4-Hittorf's phosphorus (HP)–BP. First, the phase transition of aRP and P4 molecules was reversible in the sublimation stage; then, the P4 molecules were gradually transformed into the HP structure in the transportation and deposition stage; however, the nucleation of BP quickly inhibited the growth of HP and completed the phase transition quickly; finally, the remaining P4 molecules were transformed into the BP structure, which promoted the growth of BP crystals. Crystallization kinetics explained the nucleation mechanism during the formation of BP, and the competitive nucleation between HP and BP provided the possibility for the bottom-up preparation of BP nanobelts. [ABSTRACT FROM AUTHOR]