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Zhu, Keming; Wang, Zhiying; Xu, Hanyu; Fu, Zuoling
doi: 10.1002/adom.202201182pmid: N/A
Lead halide perovskites have been very promising for versatile optoelectronic applications, whereas the inherent toxicity and instability of lead halide restrict its wide application. Herein, a kind of high‐performance multifunctional phosphor is designed based on heavy concentration Er3+‐activated lead‐free double perovskite Cs2NaBiCl6 (CNBC), which realizes the self‐sensitization of Er3+ ions and emits high‐brightness pure green emission upon dual near‐infrared (dual‐NIR) excitation. The luminescence properties can be further optimized by adding sensitizers (Yb3+/Nd3+). Interestingly, the emission intensity of the green region is heightened by 212‐fold after Yb3+ ions doping, which is 40 times higher than that of the current popular phosphors (α‐NaYF4:2%Er3+,18%Yb3+). Meanwhile, the temperature sensing properties of the thermally coupled levels (Er3+:2H11/2,4S3/2) in Cs2NaBiCl6:40%Er3+ are also investigated systematically based on the luminescence intensity ratio principle, and the maximum relative sensitivity is calculated to be as high as 1.27% K‐1 (980 nm) and 1.57% K‐1 (808 nm). Fortunately, the thermal stability and the performance for temperature readout of the studied phosphors are still maintaining a high level after doping sensitizers. The insights provided by this work will broaden the scope of lead‐free halide double perovskites in the fields of luminescence and thermometry.
Chen, Jianying; Zou, Xikun; Li, Wei; Zhang, Haoran; Zhang, Xuejie; Molokeev, Maxim S.; Liu, Yingliang; Lei, Bingfu
doi: 10.1002/adom.202200851pmid: N/A
Developing innovative narrow‐band green‐emitting phosphors featuring low thermal quenching and eco‐friendliness for white light‐emitting diode (WLED) backlights is a pivotal challenge. Benefitting from narrowband and low toxicity of green‐emitting silanized carbon dots (Si‐CDs), an efficient confinement and protection strategy through embedding Si‐CDs in mesoporous aluminas (MAs) is proposed to construct MAs and Si‐CDs composites (Si‐CDs@MAs) with superior luminescence properties. Si‐CDs@MAs phosphor exhibits green emission at 526 nm with narrow full width at half maximum of 51 nm, zero‐thermal quenching even up to 423 K (104.1%@423 K of the emission peak intensity at 298 K), and the internal quantum efficiency of 64.46%. Compared with broad‐band yellow‐emitting solid‐state Si‐CDs (S‐Si‐CDs), the thermal stability, photostability, and water stability of Si‐CDs@MAs phosphor are remarkably improved due to surface protection. The WLED backlight is fabricated with optimized Si‐CDs@MAs phosphor, which shows high luminous efficacy of 117.43 lm W−1 and wide color gamut (107% NTSC). Furthermore, this work provides the design principles of realizing stable narrow‐band solid‐state fluorescence carbon dots, suggesting its great potential for wide‐color‐gamut display application.
Hallenbeck, Zachary; Wertz, Esther A.
doi: 10.1002/adom.202200480pmid: N/A
Interactions between light and matter serve as the basis of many technologies, but the quality of these devices is inherently limited by the optical properties of their constituents. Plasmonic nanoparticles are a highly versatile and tunable platform for the enhancement of such optical properties. However, the near‐field nature of these effects has made thorough study and understanding of these mechanisms difficult. In this work, we introduce a fully confocal technique combining photoswitching super‐resolution microscopy with fluorescence lifetime imaging microscopy to study single‐molecule decay rate enhancement. We demonstrate that the technique combines a spatial resolution better than 20 nm, and a 16 ps temporal resolution. Simultaneously, an autocorrelation measurement is also performed to confirm that the data indeed originates from single molecules. This work provides insight into the various mechanisms of plasmon‐enhanced emission, and allows the study of the correlation between emission intensity and lifetime enhancement. This complicated relationship is shown to be dependent upon the relative influence of various radiative and nonradiative decay pathways. Here, we provide a platform for further study of emission mislocalization, the position‐dependent prominence of different decay pathways, and the direct super‐resolved measurement of the local density of states.
Sarkar, Swagato; Ghosh, Anik Kumar; Adnan, Mohammad; Aftenieva, Olha; Gupta, Vaibhav; Fery, Andreas; Joseph, Joby; König, Tobias A. F.
doi: 10.1002/adom.202200954pmid: N/A
Metallic nanostructures are highly attractive for refractive index sensing, as the evanescent field from the associated plasmonic resonances resides in close proximity to the adjacent analyte media. However, this benefit is often reduced due to broad plasmonic lineshapes producing poor quality factors. The rational design provides strategies for narrowing the plasmonic modes by incorporating photonic diffraction, which promotes surface lattice resonances . Due to the stringent parametric dependencies, these resonances in metallic lattices are not always feasible, particularly when a straightforward fabrication route with fewer process steps is desired. Herein, hybridized guided‐mode resonance in a 2D‐metallic photonic crystal slab (2D‐mPhCs) is introduced that ensures high‐quality hybrid modes while maintaining a simple fabrication methodology. In direct comparison to its constituent plasmonic and photonic modes, this concept is discussed for sensing applications. The “figure of merit (FOM)” is frequently regarded as a valid metric for measuring sensing performanceensuring high‐quality modes with an improved detection limit. The experimental results confirm enhanced FOM (three to six times) for the hybrid modes, in contrast to the constituent counterparts. For optoelectronic applications, such as photodetection and photocatalysis, these hybrid structures with high‐quality modes offer a promising platform to harvest light at the metal–semiconductor interfaces.
Khoury, Mario; Quard, Hugo; Herzig, Tobias; Meijer, Jan; Pezzagna, Sébastien; Cueff, Sébastien; Abbarchi, Marco; Nguyen, Hai Son; Chauvin, Nicolas; Wood, Thomas
doi: 10.1002/adom.202201295pmid: N/A
Silicon‐based micro‐ and nano‐structures for light management at near‐infrared and visible frequencies have been widely exploited for guided optics and metasurfaces. However, light emission with this material has been hampered by the indirect character of its bandgap. Here it is shown that, via ion beam implantation, light emitting G‐centers can be directly embedded within Si‐based Mie resonators previously obtained by solid state dewetting. Size‐ and position‐dependent, directional light emission at 120 K is demonstrated experimentally and confirmed by finite difference time domain simulations. It is estimated that, with an optimal coupling of the G‐centers emission with the resonant antennas, a collection efficiency of about 90% can be reached using a conventional objective lens. The integration of these telecom‐frequency emitters in resonant antennas is relevant for their efficient exploitation in quantum optics applications and more generally to Si‐based photonic metasurfaces.
Park, Jae Woo; Jung, Ye Seul; Park, Sung Hyun; Choi, Heon‐Jin; Cho, Yong Soo
doi: 10.1002/adom.202200898pmid: N/A
Photodetectors based on 2D transition‐metal dichalcogenides (TMDs) are actively investigated to find promising structures with competitive photoresponsivity. Here, a ferroelectric TMD‐based vertical photodetector with asymmetric graphene contacts is proposed, which is modulated with a poling field for controlled built‐in potentials. Thus far, no device is reported, which combines the ferroelectricity of a 2D TMD for an ideal built‐in potential with a vertical structure to reduce the channel length. A ferroelectric phase is obtained in 2D molybdenum ditelluride (MoTe2) by intensive laser irradiation, which transforms the 2H‐MoTe2 phase to distorted 1T (d1T)‐MoTe2. The subsequent poling of d1T‐MoTe2 with −8 V bias results in a photoresponsivity of ≈853 A W–1 under 532 nm illumination at zero gate voltage, which is nearly ≈4.5 times higher than that of the 2H‐MoTe2‐based reference. The achieved photoresponsivity is the best value thus far compared to the reported values for 2D MoTe2‐based UV–vis photodetectors. The origin of these enhancements is discussed in terms of changes in built‐in potential at the junctions with asymmetric graphene layers based on the adjusted band alignments driven by the poling field.
Liu, Tianhua; Lin, Qijie; Ma, Yao; Wang, Song; Chen, Hao; Wei, Yanan; Song, Yu; Shen, Liang; Huang, Fei; Huang, Hui
doi: 10.1002/adom.202201104pmid: N/A
Multifunctional organic optoelectronic devices are of great significance for the development of low‐energy consumption and space‐constrained systems. Herein, multifunctional organic photodiodes integrating transient light detection and photo‐synaptic functions in one device are unprecedentedly achieved upon readily changing the direction of the external bias. Under negative bias, the devices exhibit excellent photodetection performance with high shot‐noise‐limited specific detectivity (Dsh∗\[D_{sh}^*\] > 1013 Jones) in the range from ultraviolet, visible, to near infrared and large linear dynamic range (188 dB at 915 nm), which are among the best organic photodetectors. Interestingly, the photodiode devices change to work as organic photosynapses upon tuning the external bias to be positive. Associative learning behavior is successfully simulated in an all‐optical way, while high image recognition accuracy (>80%) is realized based on artificial neural network. The mechanism studies reveal that the interface energy barrier is critical for achieving the multi‐function in one device. Finally, the universality of electrically switchable transient light detection and photo‐synaptic functions is further studied. This work provides a novel method for constructing vertical diode‐type organic optical synapses and developing multifunctional organic electronics.
Pang, Chi; Li, Rang; Dong, Haiyun; Saggau, Christian N.; Kern, Felix L.; Potapov, Pavel; Schultz, Johannes; Lubk, Axel; Hübner, René; Kentsch, Ulrich; Zhou, Shengqiang; Helm, Manfred; Chen, Feng; Ma, Libo; Schmidt, Oliver G.
doi: 10.1002/adom.202200765pmid: N/A
The combination of plasmonic nanoparticles and optical microcavities has attracted broad interest for both fundamental and applied studies. However, the conventional scheme of plasmonic nanoparticles being located at microcavity outer surfaces suffers from serious problems such as significant radiative/scattering losses and chemical/mechanical instabilities. Here, silver nanoparticles (NPs) and dispersed ions embedded in nanomembrane‐formed whispering‐gallery‐mode (WGM) microtube cavities are prepared by ion implantations as compact and stable optoplasmonic microcavities. Upon low ion fluence implantation, dispersed silver ions are generated in the tube cavity wall, leading to a redshift of the WGM resonant cavity modes due to the increased refractive index. The silver ions start to aggregate into plasmonic NPs in the cavity wall when increasing implantation ion fluences. The competition and transition between redshift induced by the refractive index increase and blueshift induced by the formation of plasmonic NPs are investigated. Moreover, quality factor enhancement of the WGM modes is observed owing to the improved light confinement caused by the presence of NPs. This work demonstrates a convenient approach for the fabrication of stable optoplasmonic microcavities and fine tuning of resonant modes, indicating wide applications such as wavelength selective tuning and enhanced light–matter interactions.
Liu, Zhuang; Qin, Xian; Chen, Qihao; Chen, Qiushui; Jing, Yuhang; Zhou, Zhonghao; Zhao, Yong Sheng; Chen, Jingsheng; Liu, Xiaogang
doi: 10.1002/adom.202201254pmid: N/A
Materials that emit in the near‐infrared (NIR) region are at the forefront of both research and industry, mainly due to their wide applications in national security, nondestructive bioimaging, long‐wave communications, and photothermal conversion for medical care. As a key member of the luminescent materials family, metal halide perovskites have been intensively demonstrated to emit light in ultraviolet and visible regions. However, NIR‐emitting perovskites suffer from severe limitations, such as low photoluminescence quantum yield and poor chemical/optical stability, thereby preventing them from practical applications. Herein, the synthesis and growth of Cs2MoCl6 and Cs2WCl6 perovskite single crystals with ultrahigh chemical and optical resistance to heat, moisture, polar solvents, and high‐energy radiation is reported. Upon ultraviolet or blue excitation, these lead‐free single crystals emit light beyond 1100 nm, the longest wavelength ever reported for perovskite hosts. Mechanistic studies indicate that self‐trapped excitons are responsible for the NIR emission. The authors fabricate optoelectronic devices using these single crystals and demonstrate their broad applications in noninvasive palm vein imaging, night vision, and nondestructive food analysis. These results may stimulate research in the development of high‐efficiency NIR perovskite phosphors for fast, accurate biometric identification and food inspection.
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