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A self-powered CH 3 NH 3 PbI 3 photodetector (PD) based on ZnO microsphere (MS) array scaffold was reported. Through scanning electron microscopy images, a ZnO microsphere array consisted of nanosheets can be seen on ZnO mesh structure. Based on this novel structure, we first fabricated CH 3 NH 3 PbI 3 photodetector with ZnO MS as the electron selective layer and MoO 3 hole selective layer. Under light, the PDs showed the detection wavelength ranges from 300 to 800 nm, the responsivity values up to 48 mA/W, detectivity values as large as 4.5 × 10 11 Jones, on/off ratio up to 1400, and rise and fall time less than 14 ms, these results are comparable with the reported perovskite PDs. Furthermore, because of the effective absorption for ZnO microsphere in ultraviolet (UV) region, our device showed a significant UV detection performance. These results have great value on the scaffolds of perovskite materials for high performance devices. [ABSTRACT FROM AUTHOR]

Achieving high responsivity for a self-powered ultraviolet (UV) photodetector is challenging. Herein, we report a high responsivity self-powered UV photodetector based on a ZnO nanoarrays/GaN structure with a CdS insert layer whose responsivity reached as high as 176 mA W−1 at 300 nm, which is larger than the values of previously reported ZnO-based self-powered UV PDs. Moreover, based on the optimized CdS thickness with 5 cycle times, more than 1000 for the Iph/Idark ratio at the reverse biases was achieved. The device showed a good visible-blind UV photoresponse characteristic with the UV-visible responsivity ratio (R300nm/R500nm) reaching 48. Moreover, below the 350 nm UV region, the detectivity of the ZnO/CdS core–shell array PD was above 1012 cm Hz1/2 W−1, which is equivalent to that of the commercially available UV-enhanced Si photodiodes. The excellent photoelectric properties of the n-ZnO/CdS/p-GaN structure described above is due to the CdS insert layer, which was used as a carrier transition layer and realized a stepped energy level structure to effectively reduce the interfacial charge recombination and facilitate electron transfer. [ABSTRACT FROM AUTHOR]

Abstract The use of aligned one-dimensional nanostructures as scaffolds in organic-inorganic hybrid perovskite photodetectors (PDs) has attracted significant attention due to their large surface area-to-volume ratio and efficient electron transport capability in the radial direction. Here, we report CH 3 NH 3 PbI 3 (MAPbI 3) perovskite photodetectors (PDs) with Ga-doped ZnO nanorods (GZO NRs), prepared by the water bath method, as a scaffold-structure electron transport layer (ETL). Our MoO 3 hole transport layer (HTL) based perovskite PDs using GZO NRs as a scaffold showed a larger light/dark current (I ph / I dark) ratio, higher responsivity and detectivity than those of the undoped ZnO NRs/MAPbI 3 devices at zero bias. These enhancements are attributed to the incorporation of Ga atoms into the ZnO NRs, which reduce the density defect states of ZnO NRs and improves the performance of MAPbI 3 perovskite PDs. In addition, by taking advantage of the GZO NRs scaffold structure, a HTL-free perovskite PD was prepared by using graphite electrodes. The graphite-connected device shows self-powered PD performances with an I ph / I dark ratio of ~2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones, all of which are comparable with those of MoO 3 HTL based perovskite PDs. Graphical abstract Our MoO 3 hole transport layer (HTL) based perovskite PDs using GZO NRs as a scaffold showed a larger light/dark current (I ph / I dark) ratio, higher responsivity and detectivity than those of the undoped ZnO (UZO) NRs/MAPbI 3 devices at zero bias. In addition, a HTL-free perovskite PD prepared by using graphite electrodes shows self-powered PD performances with an I ph / I dark ratio of ~ 2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones, all of which are comparable with those of MoO 3 HTL based perovskite PDs. fx1 Highlights • The perovskite photodetector with GZO NRs scaffold showed a larger I ph / I dark ratio, higher responsivity and detectivity than those of the undoped ZnO devices at zero bias. • The enhancements are attributed to the incorporation of Ga elements in ZnO NRs, which reduces defect states of ZnO nanorods. • A HTL-free perovskite PD shows highly self-powered performances with the I ph / I dark ratio of ~2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones. [ABSTRACT FROM AUTHOR]

A self-powered visible-blind ultraviolet (UV) photodetector based on n -Ga:ZnO nanorods (GZO NRs)/ p -GaN heterojunction was reported, in which the n -type GZO NRs were prepared by the water bath method. In this study, we found n -GZO NRs/ p -GaN heterojunction devices showed better performance than those of n -ZnO NRs/ p -GaN heterojunction devices in terms of the ratio I ph /I dark , responsivity and detectivity. Under UV illumination with the light intensity of 1.31 mW/cm 2 , the ratio I ph /I dark for the n -GZO NRs/ p -GaN heterojunction was as high as 3.2 × 10 5 at zero bias, which is about 75 times greater than that of an un-doped device (only 4.2 × 10 3 ). Also its responsivity reached 0.23 A/W which was three times larger than that of n -ZnO NRs/ p -GaN (∼0.08 A/W). The reason n -GZO NRs/ p -GaN heterojunction displayed lager light/dark current ratio, higher responsivity and detectivity, and more reliable self-powered performance at zero bias may be that in GZO NRs, the Ga-doping reduced the defect states in the nanorods, enhanced the conductivity and electron mobility of the ZnO material and benefited the photo-generated carriers transmission. [ABSTRACT FROM AUTHOR]

An n -ZnO nanorods/ p -Si heterojunction photodetector with Al-doped ZnO (AZO) as an electron transporting layer was fabricated. The heterojunction with 20 nm AZO film showed a better characteristic than that of the device without AZO, and it displays a rectification ratio of 8470 at ±3 V and a turn-on voltage of 1.8 V. Also, based on spectral responsivity measurement, the device with AZO coating showed higher responsivity and better visible-blind detectivity than those without AZO, and the peak responsivity of the photodetector with AZO was as high as ~0.49 A/W at 354 nm. Furthermore, the photodetector with AZO layer showed a bigger UV–visible responsivity ratio ( R 354 nm / R 546 nm ) than that of the photodetector without AZO coating at −2 V. The role of AZO layer was illustrated through energy band theory and the electron transport mechanism. [ABSTRACT FROM AUTHOR]

• MgO/ZnO microsphere bilayer structure for improving the device stability with high detectivity. • The photodetectors exhibit high performance with the on/off ratio of up to more than 7.0 × 104, the linear dynamic range of 87.7 dB, and the detectivity of 1.5 × 1012 Jones, all of which are better than those of the device without MgO. • The device with the bilayer structure shows better stability compared with the device without MgO. In recent years, organic-inorganic hybrid perovskite photodetectors (PDs) have been regarded as promising next-generation PDs. However, the commercialization of the perovskite PDs still faces significant challenges, one of which is the poor stability. Herein, we demonstrate MgO/ZnO microsphere (MS) bilayer structure for improving the device stability with high detectivity. In this MgO/ZnO MS bilayer, ZnO MS array scaffold can facilitate the penetration of perovskite into nano-arrays and benefits the light harvest efficiency due to the special microsphere array structure, which behaves a big gap between aligned nanostructures. MgO passivates the interface between ZnO and perovskite, enhancing the device stability and promoting the carrier transport. Finally, our PDs with the bilayer structure exhibit high performance with the on/off ratio of up to more than 7.0 × 104, the linear dynamic range of 87.7 dB, and the detectivity of 1.5 × 1012 Jones, all of which are better than those of the device without MgO. More importantly, the device with the bilayer structure shows better stability compared with the device without MgO. Under illumination with the optical power of 314 mW/cm2, the photocurrent of the device with MgO shows almost no attenuation after continuous illumination for 30 min. In addition, after storing in air for 15 days, the performance of the device with MgO exhibits slight attenuation and the on/off ratio is still as high as 2.3 × 104, indicating that the device has good storage stability. [ABSTRACT FROM AUTHOR]