functionalities could be mimicked by using and fine tuning (by spikes) the conductance of two-terminal memristive devices. [4,6,7] Therefore, a broad range of materials, for instance, metal oxides, organic/inorganic perovskites, 2D layered materials, etc., have been used to build memristive devices, which were further employed as artificial synapses. [8][9][10][11] Despite the achievements made so far, the immediate development in particular for metal-oxide-based artificial synapses faces several major problems: a great degree of variability (both from device to device and cycle to cycle) and trivial range of linearly programmable conductance states. [12] All these obstacles must be resolved to implement error-free neuromorphic functioning. These objectives could be achieved by either exploring new material architecture or improving the performance of existing ones with a detailed understanding of fundamental change dynamics.The realization of memristive properties in metal oxide hinges on the distribution of well-known intrinsic defects or ions, mainly oxygen vacancies (O V ). [10,11,13,14] Generally, under the influence of applied electric field, local oxygen vacancy density distribution changes and thus modifies the total (two-terminal) resistance of the device. [6,15,16] Therefore, to realize the reproducible (cycle-to-cycle) and stable (device-to-device) performance, it is essential to have a better control on the oxygen vacancy/ion distribution and its movement with applied field. As a matter of fact, researchers have made several attempts to confine the oxygen ion dynamics along the preferential sites. For instance, the insertion of metal nanodots or nanoparticles, and embedded nanotip electrodes have been found to be effective in improving the cycle-to-cycle uniformity. [17][18][19] However, large size and random distribution of metal nanoparticles generate hindrance to realize reproducible performance from device to device over a larger area. Indeed, the key challenges to design metal-oxidebased artificial synapse are to have reproducible and robust (against electric pulses) performance along with large number of linearly programmable states, which is yet to be achieved.As a promising strategy, the insertion of 2D layered materials into memristive device structure offers a new possibility to improve the performance. In this scenario, few attempts have been made; however, most of them used planar configurations, which occupy relatively large space and are difficult to stack in 3D Inspired by the human brain, the quest for high-performing neuromorphic architecture has recently gained more attention, which can be achieved by two-terminal memristors. However, due to random and uncontrolled filament formation during a typical switching process, conventional memristors suffer from severe shortcomings such as temporal/spatial reproducibility as well as trivial sensitivity against applied spikes, however all these properties are crucial for accurate and quick information processing. Here, reproducible and robust...

A high‐performance transparent p‐NiO/n‐ZnO heterojunction ultraviolet photodetector with a photovoltaic mode that exploits the pyro‐phototronic effect is demonstrated. The influence of thermal treatment on ZnO films is systematically investigated, and is found to help speed up current flow due to redistribution of the pyroelectric potential within the heterojunction device. The pyrocurrent magnitude is enhanced by 1264.41% for the thermally treated device. In addition, under weak UV illumination (0.43 mW cm−2), the thermally treated device exhibits high responsivity and detectivity with respective enhancements over 5460% and 6063% compared to the pristine device. Importantly, an ultrafast response speed with rise time ≈3.92 and decay time ≈8.90 µs is achieved under self‐biased conditions. The device also maintains an impressive transparency of more than 70% in the visible region. Furthermore, the basic pyro‐phototronic properties of the device are thoroughly probed based on the influence of incident light intensity, externally applied bias, and change in transient switching frequencies. This work not only introduces a simple approach but also enables high‐performance self‐powered UV photodetection governed by the pyro‐phototronic effect and demonstrated to be suitable for future transparent optoelectronic devices.

No abstract

The optically triggered data processing and storage provides an interesting arena for developing sophisticated next-generation smart windows and computation technology. So far, transparent and flexible metal oxides have shown phenomenal optoelectronic applications. In this article, we report a photomemory of In 2 O 3 thin film deposited on glass and PET substrate using a large-scale sputtering system. The electrical characterization of a device under light and dark conditions reveals vast persistent photoconductivity (PPC) at room temperature. The PPC is systematically exploited for multibit data storage by programming with photon pulse, intensity, and source-to-drain voltage. Similarly, a high degree of persistence (>10 4 s) is achieved to retain optical information. The underlying working mechanism is attributed to the trapping of photogenerated electrons by oxygen vacancies, while corresponding holes freely participate in electrical transport even after light termination. Finally, the energy band diagram is proposed using the In 2 O 3 work function (4.26 eV measured with KPFM) and bandgap. The functional use of a transparent thin film may provide a solution of the complex multilevel programming architecture. This flexible and lightweight device can be applied in smart transparent electronics, including memories, photodetectors, and solar cells.

generate energy from the invisible radiation of the sun, while protecting us from harmful UV radiation and pollution, by employing the essential elements of a net-zero emission energy system. [3,4] The EPW is driven by UV light while simultaneously transmitting the visible spectrum, and in this way offers onsite energy generation to power micro-scale devices, for example, the internet of things. [3][4][5][6] To be environmentally effective, the system should be made from sustainable materials such as metal-oxide and organic photovoltaics. [3,[7][8][9][10][11][12] Among metal-oxides, ZnO is nontoxic, earth-abundant, and offers a bandgap of 3.2 eV, easy doping, and exciting optoelectronic processes. Tetrahedral coordination in this material results in a non-central symmetric structure and piezoelectric and pyroelectric characteristics, [13][14][15][16][17][18][19][20][21] which can be exploited by energy harvesters, for examples nano-generators [22] and other energy harvesting systems. [23][24][25] The high visible light transmittance of ZnO also makes it a potential candidate for transparent photovoltaics. [26] There have been efforts to develop ZnO based transparent photovoltaics, however, current ZnO devices typically suffer from either low photocurrent or low photovoltage. [9,[27][28][29] Despite the novelty of this class of photovoltaics, the size of the device restricts its application in an electric power window, which requires a large area. Recently, we reported a ZnO based heterostructure with various optical features, for example, room temperature excitons, demonstrated in a broadband photovoltaic [30] and pyro-phototronics [31] photodetector, which has encouraged us to develop a ZnO/NiO based highly transparent versatile 1-in. square device with enhanced performance.Here, we report a back surface field embedded all-transparent ZnO/NiO oxide heterostructure for a multi-functional EPW. First, we studied the design aspects of the AZO/ZnO/NiO device using a 1D simulation. This design revealed the vital role of the AZO layer in improving the photovoltaic performance of the ZnO/NiO via the back surface field. Following this, we studied the electrical properties of wafer-scale AZO films grown by sputtering process, and discussed the tuning of mobility and donor density (N D ). We inserted a thin layer of AZO at the interface of the ZnO/FTO and studied its photovoltaic performance Electric power windows using an all-transparent oxide photoelectric device have the potential to shield and exploit ultraviolet radiation. Herein, an Al:ZnO embedded large area all-transparent ZnO/NiO electric power window is presented. A large-scale (1-in. square) device fabricated with the structure of FTO/AZO/ZnO/NiO/AgNW exhibits a visible light transmittance >70% and photovoltaic performance with an enhanced power conversion efficiency of 3.13% under UV illumination (λ = 365 nm). The spectral attributes of this heterostructure are analyzed using I-V plots, photoresponse, and photo-carrier lifetime (τ), which reveal the co-occurren...