Single crystal reflects the intrinsic physical properties of a material, and single crystals with high-crystalline quality are highly desired for the acquisition of high-performance devices. We found that large single crystals of perovskite CH3NH3PbI3(Cl) could be grown rapidly from chlorine-containing solutions. Within 5 days, CH3NH3PbI3(Cl) single crystal as large as 20 mm × 18 mm × 6 mm was harvested. As a most important index to evaluate the crystalline quality, the full width at half-maximum (fwhm) in the high-resolution X-ray rocking curve (HR-XRC) of as-grown CH3NH3PbI3(Cl) single crystal was measured as 20 arcsec, which is far superior to so far reported CH3NH3PbI3 single crystals (∼1338 arcsec). The unparalleled crystalline quality delivered a low trap-state density of down to 7.6 × 10(8) cm(-3), high carrier mobility of 167 ± 35 cm(2) V(-1) s(-1), and long transient photovoltaic carrier lifetime of 449 ± 76 μs. The improvement in the crystalline quality, together with the rapid growth rate and excellent carrier transport property, provides state-of-the-art single crystalline hybrid perovskite materials for high-performance optoelectronic devices.
Recently, the discovery of organometallic halide perovskites provides promising routes for fabricating optoelectronic devices with low cost and high performance. Previous experimental studies of MAPbI3 optoelectronic devices, such as photodetectors and solar cells, are normally based on polycrystalline films. In this work, a high-performance planar-type photodetector fabricated on the (100) facet of a MAPbI3 single crystal is proposed. We demonstrate that MAPbI3 photodetector based on single crystal can perform much better than that on polycrystalline-film counterpart. The low trap density of MAPbI3 single crystal accounts for the higher carrier mobility and longer carrier diffusion length, resulted in a significant performance increasement of MAPbI3 photodetector. Compared with similar planar-type photodetectors based on MAPbI3 polycrystalline film, our MAPbI3 single crystal photodetector showed excellent performance with good stability and durability, broader response spectrum to near-infrared region, about 102 times higher responsivity and EQE, and approximately 103 times faster response speed. These results may pave the way for exploiting high-performance perovskites photodetectors based on single crystal.
A new self-powered broadband photodetector was fabricated by coating an n-silicon nanowire (n-Si NW) array with a layer of p-cupric oxide (CuO) nanoflakes through a new simple solution synthesis method. The p-n heterojunction shows excellent rectification characteristics in the dark and distinctive photovoltaic behavior under broadband light illumination. The photoresponse of the detector at zero bias voltage shows that this self-powered photodetector is highly sensitive to visible and near-infrared light illuminations, with excellent stability and reproducibility. Ultrafast response rise and recovery times of 60 and 80 μs, respectively, are shown by the CuO based nanophotodetector. In addition, the broadband photodetector can also provide a rapid binary response, with current changing from positive to negative upon illumination under a small bias. The binary response arises from the photovoltaic behavior and the low turn-on voltage of the CuO/Si NW device. These properties make the CuO/Si NW broadband photodetector suitable for applications that require high response speeds and self-sufficient functionality.
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