Electropolymerized Triphenylamine Network Films for High‐Performance Transparent to Black Electrochromism and CapacitanceWang, Bohan; Wang, Lingyu; Chen, Haoyan; Jia, Yanhua; Ma, Yuguang
doi: 10.1002/adom.202201572pmid: N/A
The polytriphenylamine films are prepared by electropolymerization from a precursor HPB‐6TPA with hexaphenylbenzene (HPB) core bearing six triphenylamine (TPA) units. The abundant and valuable electrochromism from transparent to black and from no to strong near‐infrared absorption are achieved from this TPA network film. The presence of residual TPA and dimeric TPA (N,N,N′,N′‐tetraphenylbenzidine) units in network film and their independent potential response attain the electrochromic behaviors. The network film possesses short response time and can realize high doping level (72%), attributed to favorable dopant ion channel caused by the twisting structure of HPB core and TPA units. The network film also shows large lightness changes and high specific capacitance (788.9 F g−[email protected] A g−1), attributed to multiple active units due to HPB core with high functionality. By regulating the voltammetric cycle number of electropolymerization, films with different lightness black colored states can be prepared conveniently to satisfy different practical needs.
Advances, Challenges, and Perspectives for Heavy‐Metal‐Free Blue‐Emitting Indium Phosphide Quantum Dot Light‐Emitting DiodesCui, Zhongjie; Yang, Dan; Qin, Shuaitao; Wen, Zhuoqi; He, Haiyang; Mei, Shiliang; Zhang, Wanlu; Xing, Guichuan; Liang, Chao; Guo, Ruiqian
doi: 10.1002/adom.202202036pmid: N/A
Quantum dot light‐emitting diodes (QLEDs), regarded as promising candidates in the next‐generation display, have attracted much attention recently. In spite of the outstanding performance of cadmium‐based (Cd‐based) QLEDs, the toxicity of Cd hinders their wide application. Indium phosphide quantum dots (InP QDs) with heavy‐metal‐free feature and competitive performance are considered to be able to replace Cd‐based QDs as emitting layer in the QLEDs. Much progress is obtained in the red‐emitting and green‐emitting InP‐based QLEDs. However, the blue‐emitting ones are faced with great challenges and are demanded on full‐color display urgently, which is limited by the inferior performance of blue‐emitting InP QDs and lack of investigations about their QLED devices. In this review, the encountered challenges for high‐quality blue‐emitting InP QDs are presented. Common strategies for blue‐emitting InP QDs, including size engineering, composition engineering, and surface engineering are presented and analyzed. The progress of blue‐emitting InP‐based QLEDs, which strongly relies on the advances of materials, is also summarized. Finally, some perspectives from device physics are provided and discussed to inspire more efficient strategies toward blue‐emitting InP‐based QLEDs.
Enabling Fast Photoresponse in Near‐Infrared Organic Phototransistors by Manipulating Minority Charge Trapping and RecombinationTang, Yu; Fu, Huaijie; Li, Ning; Hu, Yuanhong; Chen, Lixiang; Jia, Weiyao; Zhang, Qiaoming; Lei, Yanlian
doi: 10.1002/adom.202202008pmid: N/A
The organic phototransistors (OPTs) featuring built‐in amplification afford ultrahigh photoresponse. However, the response speed is usually slow in disordered OPTs, limited by the charge trapping/recombination process caused by inherent trap sites. This work studies the relationship between the photoinduced charge carrier dynamics and photoresponse characteristics in a near‐infrared (NIR) light‐sensitive OPT. It is found that the introduction of a small amount of electron acceptor into a p‐type polymer, forming a donor:acceptor bulk‐heterojunction (BHJ), in the OPT channel can dramatically improve the overall response speed of the detector. This is because the exciton dissociation and charge separation at the donor/acceptor interface not only improves the photoresponse but also reduces the minority charge trapping. Less charge trapping/recombination is essential to achieve a fast response in OPTs. As a result, the rise and fall time are improved from 1.3 and 3.5 s for the polymer‐only‐based NIR OPTs to 16 and 119 ms for the organic BHJ‐based NIR OPTs, making it suitable for use in medically relevant photoplethysmography applications.
Nonlinear Oscillation States of Optomechanical Resonator for Reconfigurable Light‐Compatible Logic FunctionsLiu, Jiawen; Gacemi, Djamal; Pantzas, Konstantinos; Beaudoin, Grégoire; Sagnes, Isabelle; Vasanelli, Angela; Sirtori, Carlo; Todorov, Yanko
doi: 10.1002/adom.202202133pmid: N/A
An optomechanical scheme is reported to implement single devices combining an electromagnetic resonator with a strongly nonlinear nanomechanical oscillator in order to realize light‐controlled logic functions. In this scheme, the nonlinear mechanical oscillations, which can be well controlled by external drives, are revealed to be sensitive to incident light due to light–matter interactions enhanced by the resonator. As a result, one can adjust the initial mechanical configurations to obtain various on‐demand responses to input optical signals, and thus realize reconfigurable logic functions (NOT, XOR, OR, AND). The single optomechanical device reported here is designed to work at the terahertz (THz) frequency domain, which is the first demonstration of a THz‐compatible logic component that processes information encoded in modulated free‐space THz light, with operation rates reaching a few kilohertz. This device also can be integrated into other micro‐electromechanical systems as THz‐compatible actuators. Moreover, the optomechanical scheme proposed in this work is applicable to other frequency ranges, such as radio frequencies (RF) or the infrared.
Deep‐Subwavelength Optical Spin Textures in Volume Plasmon Polaritons with Hyperbolic MetamaterialsGan, Shuaiwen; Shi, Peng; Yang, Aiping; Lin, Min; Du, Luping; Yuan, Xiaocong
doi: 10.1002/adom.202201986pmid: N/A
Hyperbolic metamaterials can support extremely high‐k wavevectors, also known as volume plasmon polaritons, with highly directional propagation and light confinement to deep‐subwavelength scales. The number of high‐k modes has an inverse relationship with the overall thickness of hyperbolic metamaterials. Here, the optical spin textures from high‐k mode polaritons on the surface of silica–silver multilayer hyperbolic metamaterials are studied. The results demonstrate that with an increase in the overall thickness, the spin texture changes from a twisted structure to a Néel‐type photonic skyrmion, due to the decrease in the number of high‐k modes. Moreover, the size of a single photonic skyrmion is less than 1/2 of the light wavelength, and the full width at half maximum of the spin angular momentum is less than 1/9 of the light wavelength. This work is expected to facilitate new applications of hyperbolic metamaterials, such as spin‐dependent excitation and detection devices at the deep‐subwavelength level.
How the Eurasian Jay Expands its Color Palette by Optimizing Multiple ScatteringJeon, Deok‐Jin; Ji, Seungmuk; Lee, Eunok; Kang, Jihun; D'Alba, Liliana; Shawkey, Matthew D.; Yeo, Jong‐Souk
doi: 10.1002/adom.202202210pmid: N/A
The production of structural color in nature is still incompletely understood. Multiple scattering exerts critical effects on synthetic disordered systems, but its effects on structural colors in natural materials are not yet well known. Here, electron microscopy, optical modeling, and biomimicry are used to show that variation in the thickness of the feather nanostructures creates periodic color variations in Eurasian jay wing covert feathers, with nanostructures within white feather regions being two times thicker than those in blue portions. This finding reveals that multiple scattering expands the natural color palette of the Eurasian jay by extending reflection to longer wavelengths in thicker spongy layers. Furthermore, it is found that the white color of Eurasian jay feathers is produced even in the presence of melanin due to a sufficiently thick spongy layer reflecting all visible wavelengths. Inspired by the Eurasian jay design solution, a one‐step self‐assembly method for mimicking periodic color variations in a synthetic context is described. Thus, the colors of natural color‐producing materials are modulated by changing only the thickness of the materials, leading to multiple scattering effects.
Tamm‐Plasmon Exciton‐Polaritons in Single‐Monolayered CsPbBr3 Quantum Dots at Room TemperatureYen, Meng‐Cheng; Lee, Chia‐Jung; Yao, Yung‐Chi; Chen, Yuan‐Ling; Wu, Sheng‐Chan; Hsu, Hsu‐Cheng; Kajino, Yuto; Lin, Gong‐Ru; Tamada, Kaoru; Lee, Ya‐Ju
doi: 10.1002/adom.202202326pmid: N/A
Constructing polaritonic devices in monolithic, ultra‐compact photonic architectures with monolayer‐featured exciton‐emitters is decisive to exploit the coherent superposition between entangled photonic and excitonic eigenstates for potential realizations of optical nonlinearities, macroscopic condensations, and superfluidity. Here, a feasible strategy for exciton‐polariton formations is demonstrated by implementing a Tamm‐plasmon (TP) polaritonic device with the active material composed of single‐monolayered perovskite (CsPbBr3) quantum dots (QDs). The metallic character of the TP configuration is able to concentrate its resonance mode into a confined region beyond the diffraction limit, which highly overlaps, both spatially and spectrally, with the single‐monolayered CsPbBr3 QDs embedded inside. The mode volume of the device is hence reduced dramatically, leading to an enhanced light–matter coupling strength for the polaritonic emission at room temperature. In particular, it is found that the dispersion relation of the TP polaritonic device is tunable by detuning the excitonic and photonic eigenmodes and that the polariton–polariton interaction energy is strongly dependent on the polariton's spin state. The presented strategy is a determinant step toward the realization of strong light–matter coupling and polariton spintronics in the CsPbBr3 QDs with a single‐monolayered feature.