Latest development of display technologies

In this review we will focus on recent progress in the field of two-dimensional（2D） and three-dimensional（3D）display technologies.We present the current display materials and their applications,including organic light-emitting diodes（OLEDs）,flexible OLEDs quantum dot light emitting diodes（QLEDs）,active-matrix organic light emitting diodes（AMOLEDs）,electronic paper（E-paper）,curved displays,stereoscopic 3D displays,volumetric 3D displays,light field3 D displays,and holographic 3D displays.Conventional 2D display devices,such as liquid crystal devices（LCDs） often result in ambiguity in high-dimensional data images because of lacking true depth information.This review thus provides a detailed description of 3D display technologies.

Color liquid crystal grating based color holographic 3D display system with large viewing angle

Holographic 3D display is highly desirable for numerous applications ranging from medical treatments to military affairs.However,it is challenging to simultaneously achieve large viewing angle and high-fidelity color reconstruction due to the intractable constraints of existing technology.Here,we conceptually propose and experimentally demonstrate a simple and feasible pathway of using a well-designed color liquid crystal grating to overcome the inevitable chromatic aberration and enlarge the holographic viewing angle,thus enabling large-viewing-angle and color holographic 3D display.The use of color liquid crystal grating allows performing secondary diffraction modulation on red,green and blue reproduced images simultaneously and extending the viewing angle in the holographic 3D display system.In principle,a chromatic aberration-free hologram generation mechanism in combination with the color liquid crystal grating is proposed to pave the way for on such a superior holographic 3D display.The proposed system shows a color viewing angle of~50.12°,which is about 7 times that of the traditional system with a single spatial light modulator.This work presents a paradigm for achieving desirable holographic 3D display,and is expected to provide a new way for the wide application of holographic display.

采用铜导电油墨在改性柔性基材上实现喷墨印刷

本文采用铜导电油墨在聚酰亚胺(PI)薄膜上进行喷墨印刷形成铜导电层,并研究基于铜络合物的铜导电油墨与柔性基材的相关性。本研究首先采用氧等离子体对PI薄膜表面进行改性,以测试接触角来表征改性前后薄膜表面性能的变化。通过优化等离子体反应参数使接触角降低。再利用喷墨印刷在改性前后PI薄膜上沉积铜导线,在200℃氢气环境下进行热处理,印制铜线发生烧结而收缩。采用光学显微镜(OM)、场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、非接触式三维轮廓仪和四点探针分析铜导线形状、微观结构、晶体结构及电导率。结果表明,经氧等离子体改性的PI基材上可成功沉积具有纯铜相的连续铜导线且具有良好的烧结微观结构,同时确定了铜导电油墨与基材表面性能的相关性。

Holographic storage of three-dimensional image and data using photopolymer and polymer dispersed liquid crystal films

We present holographic storage of three-dimensional（3D） images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram of real object and image of digital information are recorded in the films.The photopolymer is compared with polymer dispersed liquid crystals as holographic materials.Besides holographic diffraction efficiency of the former is little lower than that of the latter,this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field.Therefore,our study proposes a potential holographic storage material to apply in large size static 3D holographic displays,including analog hologram displays,digital hologram prints,and holographic disks.

Tunable liquid crystal grating based holographic 3D display system with wide viewing angle and large size

As one of the most ideal display approaches,holographic 3-dimensional(3D)display has always been a research hotspot since the holographic images reproduced in such system are very similar to what humans see the actual environment.However,current holographic 3D displays suffer from critical bottlenecks of narrow viewing angle and small size.Here,we propose a tunable liquid crystal grating-based holographic 3D display system with wide viewing angle and large size.Our tunable liquid crystal grating,providing an adjustable period and the secondary diffraction of the reconstructed image,enables to simultaneously implement two different hologram generation methods in achieving wide viewing angle and enlarged size,respectively.By using the secondary diffraction mechanism of the tunable liquid crystal grating,the proposed system breaks through the limitations of narrow viewing angle and small size of holographic 3D display.The proposed system shows a viewing angle of 57.4°,which is nearly 7 times of the conventional case with a single spatial light modulator,and the size of the reconstructed image is enlarged by about 4.2.The proposed system will have wide applications in medical diagnosis,advertising,education and entertainment and other fields.

A compact polymer–inorganic hybrid gas barrier nanolayer for flexible organic light-emitting diode displays

Atomic layer infiltration technology allows the formation of a nanometer-thick polymer-inorganic hybrid barrier layer in polymer material for flexible organic light-emitting diode(OLED)displays.In this study,according to transmission electron microscopy and secondary-ion mass spectrometry analysis results under various process conditions,a compact polymer-inorganic hybrid nanolayer was successfully formed in a polymer and good barrier performance was revealed with a low water vapor transmission rate under optimal process conditions.Additionally,through gas chromatography-mass spectrometry measurements after ultra-violet radiation testing,polymer out-gassing decreased compared to bare polymers.Based on barrier properties,the polymer with a polymer-inorganic hybrid barrier nanolayer was applied to a flexible OLED display as a substrate.During storage tests and folding tests,the flexible OLED display exhibits good reliability and better flexibility compared to those with an inorganic barrier layer.These results confirm that the polymer-inorganic hybrid nanolayer is suitable for barrier layer formation in flexible OLED displays.

Selective and localized laser annealing effect for high- performance flexible multilayer MoS2 thin-film transistors

We report the use of ultra-short, pulsed-laser annealed Ti/Au contacts to enhance the performance of multilayer MoS2 field effect transistors （FETs） on flexible plastic substrates without thermal damage. An analysis of the temperature distribution, based on finite difference methods, enabled understanding of the compatibility of our picosecond laser annealing for flexible poly（ethylene naphthalate） （PEN） substrates with low thermal budget （〈 200 ℃）. The reduced contact resistance after laser annealing provided a significant improvement in transistor performance including higher peak field-effect mobility （from 24.84 to 44.84 cm2-V-l.s-1）, increased output resistance （0.42 MΩ at Vgs- Vth = 20 V, a three-fold increase）, a six-fold increase in the self-gain, and decreased sub- threshold swing. Transmission electron microscopy analysis and current-voltage measurements suggested that the reduced contact resistance resulted from the decrease of Schottky barrier width at the MoS2-metal junction. These results demonstrate that selective contact laser annealing is an attractive technology for fabricating low-resistivity metal-semiconductor junctions, providing important implications for the application of high-performance two-dimensional semicon- ductor FETs in flexible electronics.

Computational approaches for fast generation of digital 3D video holograms(Invited Paper)

Several approaches for fast generation of digital holograms of a three-dimensional （3D） object have been discussed. Among them, the novel look-up table （N-LUT） method is analyzed to dramatically reduce the number of pre-calculated fringe patterns required for computation of digital holograms of a 3D object by employing a new concept of principal fringe patterns, so that problems of computational complexity and huge memory size of the conventional ray-tracing and look-up table methods have been considerably alleviated. Meanwhile, as the 3D video images have a lot of temporally or spatially redundant data in their inter- and intra-frames, computation time of the 3D video holograms could be also reduced just by removing these redundant data. Thus, a couple of computational methods for generation of 3D video holograms by combined use of the N-LUT method and data compression algorithms are also presented and discussed. Some experimental results finally reveal that by using this approach a great reduction of computation time of 3D video holograms could be achieved.

Solution processed high performance perovskite quantum dots/ZnO phototransistors

Phototransistors that can detect visible light have been fabricated using solution processed zinc oxide channel/zirconium oxide gate insulator thin film transistors(TFTs)and room temperature synthesized perovskite quantum dots(PeQDs)as active layer.Typical ZnO thin film transistors did not show a photocurrent under visible light illumination.However,ZnO TFTs decorated with PeQDs exhibited enhanced photocurrent upon exposure to visible light.The device had a responsivity of 567 A/W(617 A/W),a high detectivity of 6.59×10^(13)Jones(1.85×10^(14)J)and a high sensitivity of 10^(7)(10^(8))under green(blue)light at a low drain voltage of 0.1 V.The high photo-responsivity and detectivity under green light resulted from the combination of short ligands in the QDs films and the high mobility of the spray coated ZnO films.Those results are relevant for the development of low cost and low energy consumption phototransistors working in the visible range.