Developing tailored micro/nanostructure interfaces is an effective way to make novel optoelectronic devices or enhance their performances. Here we report the fabrication of a PEDOT:PSS/ZnO micro/nanowire-based self-powered UV photosensor. The generation of photocurrent at zero bias is attributed to the separation of photogenerated electron-hole pairs within the built-in electric field at the PEDOT:PSS/ZnO interface upon UV light illumination. Furthermore, the piezotronic effect on the UV photoresponsivity under different strains is investigated, which is due to the modification of energy band diagram at the p-n heterojunction by strain-induced piezoelectric polarization. This study demonstrates a prospective approach to engineering the performance of a photodetector through straining and may offer theoretical supporting in future optoelectronic device fabrication and modification.
In this work, a high-performance, forming-free memristor based on Au/ZnO nanorods/AZO (Al-doped ZnO conductive glass) sandwich structure has been developed by rapid hydrogen annealing treatment. The Ron/Roff rate is dramatically increased from ∼10 to ∼10(4) after the surface treatment. Such an enhanced performance is attributed to the introduced oxygen vacancies layer at the top of ZnO nanorods. The device also exhibits excellent switching and retention stability. In addition, the carrier migration behavior can be well interpreted by classical trap-controlled space charge limited conduction, which verifies the forming of conductive filamentary in low resistive state. On this basis, Arrhenius activation theory is adopted to explain the drifting of oxygen vacancies, which is further confirmed by the time pertinence of resistive switching behavior under different sweep speed. This fabrication approach offers a useful approach to enhance the switching properties for next-generation memory applications.
With multiphoton‐pumped lasing, 2D all‐inorganic CsPbI3 perovskite nanoplates demonstrate a wide range of applications which results from its high crystalline quality and a nearly perfect naturally formed whispering gallery mode cavity. However, there still remains a difficulty in controllable synthesizing 2D CsPbI3 nanosheets with high crystalline quality. In this work, high‐quality 2D CsPbI3 perovskite nanosheets have been synthesized successfully with controllable morphology through space‐confined vapor‐phase epitaxial growth. More importantly, the morphology and crystalline quality of CsPbI3 perovskite nanosheets could be easily tuned by adjusting the diffusion and growth process achieved by adjusting the space‐confined distance and growth temperature. The typical square‐like CsPbI3 perovskite nanosheets can be as thin as 6.0 nm with a lateral size of 10.0 µm. The photoluminescence emission properties show a distinct dependence on thickness of these as‐grown CsPbI3 perovskite nanosheets. In addition, the as‐fabricated CsPbI3 perovskite nanosheets demonstrate one‐photon and two‐photon excitation‐pumped lasing with low‐threshold and high‐quality factor. The excellent multiphoton‐pumped lasing properties of the CsPbI3 perovskite nanosheets are attributed to their high crystalline quality, implying great promise for future applications in high‐performance optoelectronics.
Strain-induced piezoelectric potential (piezopotential) within wurtzite-structured ZnO can engineer the energy-band structure at a contact or a junction and, thus, enhance the performance of corresponding optoelectronic devices by effectively tuning the charge carriers' separation and transport. Here, we report the fabrication of a flexible self-powered ZnO/Spiro-MeOTAD hybrid heterojunction ultraviolet photodetector (UV PD). The obtained device has a fast and stable response to the UV light illumination at zero bias. Together with responsivity and detectivity, the photocurrent can be increased about 1-fold upon applying a 0.753% tensile strain. The enhanced performance can be attributed to more efficient separation and transport of photogenerated electron-hole pairs, which is favored by the positive piezopotential modulated energy-band structure at the ZnO-Spiro-MeOTAD interface. This study demonstrates a promising approach to optimize the performance of a photodetector made of piezoelectric semiconductor materials through straining.
Interface modulation for broad-band light trapping and efficient carrier collection has always been the research focus in solar cells, which provides the most effective way to achieve performance enhancement. In this work, solution-processed 3D ordered ZnO/Cu2O nanoheterojunctions, consisting of patterned n-ZnO nanorod arrays (NRAs) and p-Cu2O films, are elaborately designed and fabricated for the first time. By taking advantage of nanoheterojunctions with square patterned ZnO NRAs, solar cells demonstrate the maximum current density and efficiency of 9.89 mA cm(-2) and 1.52%, which are improved by 201% and 127%, respectively, compared to that of cells without pattern. Experimental analysis and theoretical simulation confirm that this exciting result originates from a more efficient broad-band light trapping and carrier collection of the 3D ordered ZnO/Cu2O nanoheterojunctions. Such 3D ordered nanostructures will have a great potential application for low-cost and all oxide solar energy conversion. Furthermore, the methodology applied in this work can be also generalized to rational design of other efficient nanodevices and nanosystems.
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