Biodegradability, low-voltage operation, and flexibility are important trends for the future organic electronics. High-capacitance dielectrics are essential for low-voltage organic field-effect transistors. Here we report the application of environmental-friendly cellulose nanopapers as high-capacitance dielectrics with intrinsic ionic conductivity. Different with the previously reported liquid/electrolyte-gated dielectrics, cellulose nanopapers can be applied as all-solid dielectrics without any liquid or gel. Organic field-effect transistors fabricated with cellulose nanopaper dielectrics exhibit good transistor performances under operation voltage below 2 V, and no discernible drain current change is observed when the device is under bending with radius down to 1 mm. Interesting properties of the cellulose nanopapers, such as ionic conductivity, ultra-smooth surface (~0.59 nm), high transparency (above 80%) and flexibility make them excellent candidates as high-capacitance dielectrics for flexible, transparent and low-voltage electronics.

The outstanding performances of nanostructured all-inorganic CsPbX3 (X = I, Br, Cl) perovskites in optoelectronic applications can be attributed to their unique combination of a suitable bandgap, high absorption coefficient, and long carrier lifetime, which are desirable for photodetectors. However, the photosensing performances of the CsPbI3 nanomaterials are limited by their low charge-transport efficiency. In this study, a phototransistor with a bilayer structure of an organic semiconductor layer of 2,7-dioctyl [1] benzothieno[3,2-b] [1] benzothiophene and CsPbI3 nanorod layer was fabricated. The high-quality CsPbI3 nanorod layer obtained using a simple dip-coating method provided decent transistor performance of the hybrid transistor device. The perovskite layer efficiently absorbs light, while the organic semiconductor layer acts as a transport channel for injected photogenerated carriers and provides gate modulation. The hybrid phototransistor exhibits high performance owing to the synergistic function of the photogating effect and field effect in the transistor, with a photoresponsivity as high as 4300 A W−1, ultra-high photosensitivity of 2.2 × 106, and excellent stability over 1 month. This study provides a strategy to combine the advantages of perovskite nanorods and organic semiconductors in fabrication of high-performance photodetectors.Electronic supplementary materialThe online version of this article (10.1007/s40820-018-0210-8) contains supplementary material, which is available to authorized users.

Distinguishable detection of the ultraviolet, visible, and infrared spectrum is promising and significant for the super visual system of artificial intelligences. However, it is challenging to provide a photosensor with such broad spectral response ability. In this work, the ultraviolet, visible, and infrared spectrum is distinguished by developing serial photosensors based on perovskite/carbon nanotube hybrids. Oraganolead halide perovskites (CH NH PbX ) possess remarkable optoelectronic properties and tunable optical band gaps by changing the halogens, and integration with single-walled carbon nanotubes can further improve their photoresponsivities. The CH NH PbCl -based photosensor shows a responsivity up to 10 A W to ultraviolet and no obvious response to visible light, which is superior to that of most ultraviolet sensors. The CH NH PbBr -based photosensor exhibits a high responsivity to visible light. Serial devices of the two hybrid photosensors with comparable electric and sensory performances can distinguish the spectrum of ultraviolet, visible, and infrared even with varying light intensities. The photosensors also demonstrate excellent mechanical flexibility and bending stability. By taking full advantages of the oraganolead halide perovskites, this work provides flexible high-responsivity photosensors specialized for ultraviolet, and gives a simple strategy for distinguishable detection of ultraviolet, visible, and infrared spectrum based on the serial flexible photosensors.

latest power conversion efficiency (PCE) over 22.7%, demonstrating their great potential in photovoltaics. [14] On the other hand, OHP-based photodetectors have also attracted significant interest in recent years. [4,[15][16][17] Previous studies have revealed that OHPs are suitable for light detection with the promising property in terms of excellent photoresponsivity, large photocurrents, and fast respond speed. [18][19][20][21] Xie and co-workers reported first that photodetectors with CH 3 NH 3 PbI 3 (MAPbI 3 ) polycrystalline film as active layers exhibited a broad photoresponse range from 780 to 310 nm. [22] Horváth et al. have synthesized OHP nanowires via a lowtemperature crystallization technique by using a simple and low cost slip coating method, and the nanowire-based photodetector exhibited a fast photoresponse with short rise and fall times. [23] However, the limited long-term stability of the OHPs remains as the bottleneck issue for further improving the performance of OHP-based photoelectronics, because water invasion and oxygen erosion to the materials can destroy their crystal structure. [24][25][26][27][28][29] The large amount of grain boundaries of the polycrystalline OHP films would provide with more reacting sites with water and oxygen molecules. Although the OHP nanowires process rather high crystallinity, the large surfaceto-volume ratio of the nanowires could facilitate the destruction processes. [30][31][32][33] Microwires (MWs) of OHPs can be also fabricated and applied in photodetectors which showed decent photosensing performance. [32,34] Moreover, we realized that the high-crystallinity OHP MWs present much less grain boundaries as compared to polycrystalline films, at the same time, possess much lower surface-to-volume ratio than nano wires. Such combined properties can provide the OHP MWs with superior resistance to moisture and oxygen as compare to conventional films or nanowires, and thus are expected to improve the longterm stability of the OHP-based photoelectronics.In this work, we report long-term stable photodetectors on the basis of MAPbI 3 MWs which are fabricated by a dip-coating method which is more suitable for large-scale and low-cost devices fabrication. The distribution of the MAPbI 3 MWs in the devices can be adjusted by changing the dip-coating parameters, thus providing the MAPbI 3 MWs-based photodetectors (MMPs) Oraganolead halide perovskites (OHPs) present remarkable optoelectronic properties, and thus possess extensive applications in photovoltaic devices and photodetectors. However, the OHP-based devices severely suffer from low environmental stability because of water invasion and oxygen erosion to the materials. In this work, this challenge is overcome by utilizing the unique advantages of the microwire structure. OHP microwires, which can be fabricated by simple and low-cost dip coating method, present superior resistance to moisture as compare to conventional OHP films or nanowires, thanks to their combined properties of high-crystallinity and low surface...

Thiocyanate-based perovskite (SCN-PVSK) photodetectors have been fabricated by introducing lead thiocyanate precursor. Incorporating SCN groups into CH 3 NH 3 PbI 3 can significantly improve the device stability in air. Compared with pure CH 3 NH 3 PbI 3 films, SCN-PVSK films have larger grain size and reduced trap states. The perovskite layers can be prepared by a simple solution method in air. Solvent effects on the crystallization of SCN-PVSK films have also been investigated. It is found that highly uniform, pinhole-free perovskite films can be obtained utilizing the N,N-dimethylformamide (DMF) solution of Pb(SCN) 2 . The SCN-PVSK based photodetectors performed a high responsivity of 12.3 A/W and a decent detectivity over 1.3 × 10 13 Jones. More important, the SCN-PVSK based twoterminal photodetectors, without encapsulation, have shown great stability with 92% of the initial photocurrent being retained after storage in air (relative humidity >50%) for 10 days, whereas the value is only 10% for pure CH 3 NH 3 PbI 3 devices tested under the same conditions.