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All-inorganic Bi-based perovskites have attracted much attention due to their excellent stability, environmentally friendly, and low-cost solution processability. However, due to the large exciton binding energy and small light absorption coefficient, the performance of the Bi-based perovskite photodetector (PD) is far behind of the traditional Pb-based perovskite PDs. In this work, the lead-free all-inorganic Cs3Bi2I9 (CBI) perovskite single crystal was synthesized by a space-confined antisolvent-assisted crystallization method for high-performance, semi-transparent, and self-driven PDs with an ITO/SnO2/CBI/PTAA/Au/ITO structure. Electrical and optical properties of Au/ITO transparent electrode were studied considering its figure of merit and device quantum efficiency through optimizing the Au thickness. Finally, our optimized semi-transparent device showed excellent self-driven performance with a large on/off ratio of ∼5700, a high responsivity of 52.06 mA/W, a high detectivity of >1012 Jones, and a large linear dynamic range of up to 140.7 dB. In addition, our device demonstrated excellent characteristics to the weak light detection and the long-term stability. The Au/ITO electrode was adopted and tailored to balance the device performance and transparency, which provides a good route for developing high-performance and transparent devices in the future. [ABSTRACT FROM AUTHOR]

Wide bandgap SnO2 usually shows n-type conductivity due to intrinsic defects. Herein, we demonstrate the achievement of p-type conduction in SnO2 with a two-step process, in which 3.3 at. % Mg-doped SnO2 epitaxial films were first grown on c-Al2O3 by pulsed laser deposition and then annealed in an oxygen atmosphere at proper temperature and time. An activation energy of around 85 meV revealed by temperature-dependent resistance measurements verifies Mg as a shallow acceptor in the p-type doping of SnO2. The post-annealing treatment at suitable temperature and time was found to be crucial to greatly enhance the p-type conductivity of Mg-SnO2 by removing the interstitial Mg while maintaining the substitutional Mg in the SnO2 lattice. A hole concentration of 1.43 × 1017 cm−3 and a hole mobility of 4 cm2 V−1 s−1 as determined by Hall-effect measurements were achieved for a sample annealed at optimized conditions of 600 °C and 0.5 h. The achievement of high-quality p-type Mg-SnO2 epitaxial films demonstrates high potential in developing advanced optoelectronic devices based on p-n junctions of SnO2. [ABSTRACT FROM AUTHOR]

Bi1-xCexFeO3 (x=0, 0.05, 0.1, 0.15, and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si3N4/Si and fluorine-doped SnO2 glass substrates by sol-gel technique, respectively. The effect of Ce doping on the microstructure, electrical and magnetic properties of BCFO films was studied. Compared to counterparts of BiFeO3 (BFO) film, the fitted Bi 4f7/2, Bi 4f5/2, Fe 2p3/2, Fe 2p1/2, and O 1s peaks for Bi0.8Ce0.2FeO3 film shift toward higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58, and 0.49 eV, respectively. Raman redshifts of 2–4 cm-1 and shorter phonon lifetimes for the Bi0.8Ce0.2FeO3 film might be related to anharmonic interactions among Bi–O, Ce–O, (Bi, Ce)–O, and Fe–O bonds in the distorted oxygen octahedron. Compared to the pure counterparts, the dielectric and ferroelectric properties of the Bi0.8Ce0.2FeO3 film are improved due to the decreased oxygen vacancies by the stabilized oxygen octahedron. Current density values for the BFO and Bi0.8Ce0.2FeO3 film capacitors are 9.89×10-4 and 5.86×10-5 A/cm2 at 10 V, respectively. The current density–applied voltage characteristics indicate that the main conduction mechanism for the BCFO capacitors is the interface-controlled Schottky emission. Both the in-plane and out-of-plane magnetization–magnetic field hysteresis loops reveal that the saturation magnetization values of the BCFO films increase with increasing the Ce concentration. The enhanced magnetic properties for the BCFO films might be attributed to the presence of Fe2+ caused by oxygen vacancies, the suppressed spiral spin structure, and/or the increased canting angle induced by Ce doping. [ABSTRACT FROM AUTHOR]

P-poly(9, 9-diethylfluorene)/n-silicon nanowire (SiNW) heterojunctions were prepared by spin coating p-type conductive organic polymer on as-prepared n-SiNWs, which were fabricated by electroless metal deposition method. This hybrid nanowire p-n heterojunction shows good rectifying behavior with turn-on voltage of about 1 V at room temperature. Temperature-dependent current-voltage properties in the range of 253–413 K were investigated and they follow the standard p-n heterojunction electron transport mechanism. The hybrid nanowire heterojunction shows good photovoltaic properties and good sensitivity toward visible light, and a responsivity of 3.23 mA/W under a reverse bias of 10 V was obtained. These results present potential applications in the future nanoelectronic and photonic devices based on organic and inorganic p-n heterojunction arrays. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) with MgZnO/ZnO/MgZnO double heterojunction structure have been fabricated and the room temperature electroluminescence (EL) spectra have been studied. With the help of double heterostructure, LEDs show better visible EL performance than that of LED with ordinary p-i-n structure. By replacing ZnO film with ZnO nanorod arrays in this double heterostructure, strong ultraviolet EL emission around 380 nm was achieved. The ZnO-nanorod-based double heterostructured light-emitting diode exhibits superior stability with an intensity degradation of less than 3% over 8 h. The EL mechanisms were discussed in terms of carrier confinement and carrier transport based on semiconductor heterojunction theory. [ABSTRACT FROM AUTHOR]

n-ZnO/p-Si heterojunction light emitting devices with and without a NiO intermediate layer were fabricated using a radio frequency magnetron sputtering system. Electroluminescence measurements revealed that the device with the NiO intermediate layer exhibits a sharper and stronger orange emission peaks at ∼670 nm compared with that of the device without the NiO layer. And the light output-current characteristic of the n-ZnO/NiO/p-Si heterojunction device follows a nearly linear relationship (L ∝ I) rather than the superlinear relationship (L ∝ I1.5) for the n-ZnO/p-Si heterojunction device. This work indicates that the NiO intermediate layer could effectively improve the performance of the n-ZnO/p-Si heterojunction light emitting device. [ABSTRACT FROM AUTHOR]

n-ZnO/HfO2/p-GaN based heterojunction light emitting diodes were fabricated using a radio frequency magnetron sputtering system. The electroluminescence measurements revealed that dominant violet emissions centered at around 415 nm were emitted and improved performances were observed for the devices with the HfO2 intermediate layer; the color of the devices could be tuned from violet (0.18, 0.10) to cold white (0.22, 0.20) by varying the Ar/O2 flow ratio during the deposition of HfO2, which are probably ascribed to the deep level emission bands in ZnO. The results were studied by peak-deconvolution with Gaussian functions and were discussed in terms of band diagram of the heterojunctions. [ABSTRACT FROM AUTHOR]

We fabricate an ultraviolet (UV)/orange bicolor light emitting diode (LED) based on an n-ZnO/n-GaN isotype heterojunction, which presents a sharp ultraviolet emission centered at 367 nm and a broad orange emission centered at 640 nm under forward and reverse biases, respectively. Time dependence electroluminescence (EL) measurements reveal that this device shows good stability. The electroluminescence mechanism of the bicolor light emitting diode is discussed in terms of the material properties of the interfacial layer and the luminescence properties of the device in this work. [ABSTRACT FROM AUTHOR]

Organic solar cells based on vertically aligned zinc oxide nanorod arrays (ZNR) in an inverted structure of indium tin oxide (ITO)/ZNR/poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester(P3HT:PCBM)/MoO3/aluminum(Al) were studied. We found that the optimum MoO3 layer thickness condition of 20 nm, the MoO3 can effectively decrease the probability of bimolecular recombination either at the Al interface or within the active layer itself. For this optimum condition we get a power conversion efficiency of 2.15%, a short-circuit current density of 9.02 mA/cm2, an open-circuit voltage of 0.55V, and a fill factor of 0.44 under 100 mW/cm2 irradiation. Our investigations also show that the highly crystallized ZNR can create short and continuous pathways for electron transport and increase the contact area between the ZNR and the organic materials. [ABSTRACT FROM AUTHOR]

ZnO nanorod strain driving transistor (SDT) with 107 scale 'on'-'off' ratio has been fabricated on Kapton substrate by a single-step hydrothermal reaction. The transistor is driven by strain due to the change in Schottky barrier height caused by piezoelectric effect as well as the change of contact area between ZnO bridging nanorods. Moreover, via utilizing two SDTs on the top and bottom surfaces of the substrate as two complementary metal-oxide-semiconductor transistors, several logic operations such as inverter, NAND, NOR, XOR, MUX, and DEMUX with good rectifying behaviors have been demonstrated. [ABSTRACT FROM AUTHOR]

n-ZnO/p-silicon nanowire (SiNW) photodiodes were prepared by radio frequency reactive magnetron sputtering of n-type zinc oxide at room temperature on photoresist filled p-SiNWs, which were fabricated by electroless metal deposition method at 323 K. Our n-ZnO/p-SiNW photodiodes showed good temperature- and light-intensity dependence. They exhibited strong responsivities of 19.2 and 2.5 A/W for 254 and 1000 nm photons, respectively, under a reverse bias of 2 V with a strong peak of responsivity near 390 nm, the wavelength corresponding to the band gap of ZnO. These results present potential applications of n-ZnO/p-SiNW photodetectors in deep ultraviolet and near infrared regions. [ABSTRACT FROM AUTHOR]

A response to a letter to the editor about the article "Deep ultraviolet and near infrared photodiode based on n-ZnO/p-silicon nanowire heterojunction at low temperature," is presented.

Organic solar cells based on vertically aligned zinc oxide nanorod arrays (ZNR) in an inverted structure of indium tin oxide (ITO)∕ZNR∕poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester(P3HT:PCBM)∕MoO(3)∕aluminum(Al) were studied. We found that the optimum MoO(3) layer thickness condition of 20 nm, the MoO(3) can effectively decrease the probability of bimolecular recombination either at the Al interface or within the active layer itself. For this optimum condition we get a power conversion efficiency of 2.15%, a short-circuit current density of 9.02 mA∕cm(2), an open-circuit voltage of 0.55V, and a fill factor of 0.44 under 100 mW∕cm(2) irradiation. Our investigations also show that the highly crystallized ZNR can create short and continuous pathways for electron transport and increase the contact area between the ZNR and the organic materials.