A core–shell heterojunction has been developed to fabricate efficient optoelectronic devices by optimizing the light absorption and promoting the generation and extraction of charge carriers. Herein, the CdS@CsPbBr3 core–shell microwire (MW) heterojunction was structured via a two-step chemical vapor deposition and was further used to fabricate a UV–Vis photodetector. The photodetector performance is greatly dependent on the thickness of the CsPbBr3 shell. Growth time of 60 min could produce about 80 nm thick CsPbBr3 shell with excellent coverage and adhesion, resulting in optimized performance parameters. As compared with bare cadmium sulfide (CdS) MW photodetector, the CdS@CsPbBr3 core–shell MW heterojunction photodetector exhibits relatively high ratio of photocurrent and dark current (104), much higher light responsivity (319.79 A W−1) and faster response time (6.6 ms). The responsivity is 3.3 times to the value of bare CdS photodetector and the photocurrent increases nearly 10 times. The significant performance parameters mainly result from the formation of a type-II energy band structure and the reduction of the defects states on CdS surface, leading to the obviously improved carriers transport process. The results indicate that the CdS@CsPbBr3 core–shell MW heterojunction is a promising potential candidate to construct high-performance electronic and optoelectronic devices.

Metal halide perovskites (MHPs) show excellent optoelectronic properties and exhibit great potential applications in optoelectronic devices, such as solar cells (SCs), photodetectors, light-emitting diodes (LEDs), lasers, and so on. Vapor-phase synthesis provides an important way to grow large-scale, high-quality MHP thin films and micro-/nanostructures, exhibiting wide applications in constructing all kinds of optoelectronic devices. In this review, we systematically summarize the growth of perovskite thin film and the nano-/microstructure by vapor-phase synthesis. The detailed classification of vapor-phase synthesis is first introduced, and the effects of the substrates on the growth process are discussed subsequently. Then, the applications of perovskite thin films and micro-/nanostructures grown by vapor-phase synthesis in SCs, photodetectors, LEDs, lasers, and so forth, are discussed in detail. Finally, the conclusions and outlook are presented.

Inorganic perovskite cesium lead halide (CsPbBr3) has attracted considerable attention because of its particularly excellent optoelectronics properties and high stability in humidity environments. Here, highly crystalline CsPbBr(3)films with different morphologies and grain sizes were prepared via a one-step low pressure chemical vapor deposition (CVD). The structure-activity relationship between film microstructure and photodetectors (PDs) performance are investigated. The CsPbBr3PD prepared at similar to 190 degrees C possess an excellent response in the UV-Vis region and exhibits a fast response time of 0.7 ms/1.0 ms. Under 405 nm laser irradiation, the PD has a high responsivity, detectivity, external quantum efficiency, and switch ratio of 3.49 A W-1, 1.50 x 10(13)Jones, 1075.4%, and 3.29 x 10(5), respectively. More importantly, the PD maintains 93% of original photocurrent when exposed to air for 28 d, which demonstrates excellent stability. At the same time, the CsPbBr(3)films prepared via CVD are not dependent on the substrate, and the PDs exhibit similar performance on glass, SiO2/Si and polyimide substrates. The photocurrent of the flexible PD is maintained at 86% of the initial device performance parameters after 1000 bending cycles. These results indicate that the CsPbBr(3)perovskite films prepared via CVD have great potential for application in high-performance, stable and flexible PDs.

Organic–inorganic hybrid perovskites are considered as a class of star materials for optoelectronic devices. However, the stability is one of the big issues. Herein, an MAPbI3 perovskite film with high stability is fabricated using chemical vapor deposition (CVD). The stability and performance of the MAPbI3 photodetector are further improved by constructing an MAPbI3 heterojunction with the organic semiconductor C8BTBT. The MAPbI3/C8BTBT heterojunction photodetector shows a wide spectral response range from ultraviolet to visible light and a fast response time of 30 ms/12 ms. Under laser irradiation at 405 nm, the responsivity of the MAPbI3/C8BTBT heterojunction photodetector reaches 6.09 A W−1, which is an 11.9‐fold improvement as compared with the MAPbI3 photodetector (0.51 A W−1). After storage under ambient conditions (humidity of ≈35%) for 2 months, the MAPbI3/C8BTBT heterojunction photodetector still exhibits excellent stability and the photocurrent maintains 93.7% of its initially measured value. The excellent stability under ambient conditions is likely the result of the stable MAPbI3 film that is fabricated via CVD and the protection of the organic semiconductor layer C8BTBT. The results provide a feasible route toward high‐performance and stable perovskite optoelectronic devices by combining CVD with perovskite heterojunctions.

Perovskite cesium lead halide (CsPbBr3) has attracted considerable attention due to its excellent optoelectronic properties and superior stability against moisture, oxygen, light, and heat. In this work, the micro-environment controlled chemical vapor deposition (CVD) method has been adopted to synthesize high-quality single-crystalline CsPbBr3 microstructures, including microwires, microplates and triangular pyramids. Moreover, the structure-activity relationship between the material microstructures and the device properties is illustrated. The results show that photodetectors based on a single horizontal CsPbBr3 microwire exhibit a high responsivity (312.2 A W-1) and a fast response time of 5.8 ms. Photodetectors based on a single CsPbBr3 microplate exhibit a responsivity of 1.74 A W-1 and a response of 10 ms. These results indicate that the CsPbBr3 microwire photodetector is characterized by a higher photodetector performance when compared to the microplate due to its excellent crystallization quality and the Fabry-Pérot cavity effect in the microwire. Furthermore, the flexible CsPbBr3 microwire photodetector was demonstrated on a mica substrate. The results show that the photocurrent can be maintained at 90% after 3000 cycles at a bending radius of 2.5 mm. This work demonstrates the structure-activity photodetector performance, which is essential to develop a full understanding about high-performance optoelectronic devices based on all-inorganic lead halide perovskite materials.

Photoelectronic properties can be effectively modulated by external mechanical stimulation, which have been widely researched on materials with non-centrosyrnmetric wurtzite structure. Topological insulator (TI) materials with symmetric crystal structure have been theoretically predicted that its photoelectronic properties would also be greatly modulated through strain modulation effect. Here, for the first time, we experimentally demonstrate the strain modulation effect of TI Bi2Se3 nanowires (NWs), opening an innovative way to enhance the optoelectronic performance of TI materials. Single-crystal TI Bi2Se3 NWs were synthesized via a micro-environmental control chemical vapor deposition method. Based on these NWs, a high-performance photodetector (PD) with high responsivity, and broadband detection range from ultraviolet to near-infrared were fabricated. By introducing an external 0.54% compressive strain, the photocurrent and responsivity were enhanced by 97% and 503%, respectively, upon excitation by 442 nm light with an intensity of 17.6 mW/cm(2). A theoretical model of the schematic energy band diagram was proposed to illustrate the enhancement mechanism. The results of theoretical calculation indicate that the conduction band of the TI can be modulated by strain, which can then influence the metal-semiconductor (M-S) junction potential for charges transport. This study reports a high-quality TI Bi2Se3 NWs based strain-modulated PDs, broadening the family of strain modulation materials system, and offering a promising material for high-performance broadband detectors.

The piezo-phototronic effect utilizes the piezo-polarization charge to modify the energy band diagram at the local interface/junction and manipulate the optoelectronic processes of charge carriers, which have provided a promising approach to improve the performance of photoelectric devices. In this paper, we report on the fabrication of single ultra-fine CdTe nanowire (NW) piezo-phototronic photodetectors (PDs). The structure and morphology of the as-synthesized CdTe NWs is characterized in detail. The result shows that the CdTe NWs have a single crystalline zinc blende structure, with its diameter narrowing to about 20 nm. The flexible Ag-CdTe NW-Ag lateral PDs are prepared on the polyethylene terephthalate substrate, showing a broadband photoresponse from ultraviolet to near infrared (NIR) (325-808 nm). By introducing the piezo-phototronic effect, strain-induced piezoelectric polarization charges effectively enhance the performances of the NIR PDs (808 nm) by 430% in photocurrent and 427% in photoresponsivity. The physical mechanism is carefully investigated by analyzing the energy band diagrams at the local metal–semiconductor interface under mechanical deformations. The ultra-fine structure with a larger piezoelectric coefficient is attributed to the enhancement of photoresponsivity. This investigation demonstrates an efficient prototype of the broad-wavelength piezo-phototronic PD based on the ultra-fine CdTe NWs, which provides an effective route to enhance the performance of optoelectronic devices.The piezo-phototronic effect utilizes the piezo-polarization charge to modify the energy band diagram at the local interface/junction and manipulate the optoelectronic processes of charge carriers, which have provided a promising approach to improve the performance of photoelectric devices. In this paper, we report on the fabrication of single ultra-fine CdTe nanowire (NW) piezo-phototronic photodetectors (PDs). The structure and morphology of the as-synthesized CdTe NWs is characterized in detail. The result shows that the CdTe NWs have a single crystalline zinc blende structure, with its diameter narrowing to about 20 nm. The flexible Ag-CdTe NW-Ag lateral PDs are prepared on the polyethylene terephthalate substrate, showing a broadband photoresponse from ultraviolet to near infrared (NIR) (325-808 nm). By introducing the piezo-phototronic effect, strain-induced piezoelectric polarization charges effectively enhance the performances of the NIR PDs (808 nm) by 430% in photocurrent and 427% in photorespon...

Flexible perovskite solar cells (f-PSCs) have attracted great attention due to their promising commercial prospects. However, the performance of f-PSCs is generally worse than that of their rigid counterparts. Herein, it is found that the unsatisfactory performance of planar heterojunction (PHJ) f-PSCs can be attributed to the undesirable morphology of electron transport layer (ETL), which results from the rough surface of the flexible substrate. Precise control over the thickness and morphology of ETL tin dioxide (SnO2) not only reduces the reflectance of the indium tin oxide (ITO) on polyethylene 2,6-naphthalate (PEN) substrate and enhances photon collection, but also decreases the trap-state densities of perovskite films and the charge transfer resistance, leading to a great enhancement of device performance. Consequently, the f-PSCs, with a structure of PEN/ITO/SnO2/perovskite/Spiro-OMeTAD/Ag, exhibit a power conversion efficiency (PCE) up to 19.51% and a steady output of 19.01%. Furthermore, the f-PSCs show a robust bending resistance and maintain about 95% of initial PCE after 6000 bending cycles at a bending radius of 8 mm, and they present an outstanding long-term stability and retain about 90% of the initial performance after >1000 h storage in air (10% relative humidity) without encapsulation.