devices, sensing, biological imaging, and display [1][2][3][4] due to their long-life characteristics. Carbon dots (CDs) as the emerging carbon nano-luminescent materials, due to their unique optical properties, low toxicity, chemical inertness, and easy preparation, [5][6][7][8] stand out among many luminescent materials and become the important parts of RTP materials. Different CDs fluoresce in unique ways under different states. CDs in dilute solutions have different photophysical properties compared with solid or highconcentration solutions. Moreover, CDs follow the aggregation-caused quenching (ACQ) effect. [9] For example, the luminescence of CDs will be weakened in the solid-state. The reasons for the quenching are the excessive fluorescence resonance energy transfer (FRET) and the π-π stacking interaction between the carbon cores, resulting in the non-radiative loss of the excited state. [10][11][12][13] The luminescence of CDs in the solid-state is obviously quenched due to the ACQ effect, which severely limits their development in the direction of RTP materials.Theoretically, the best way to prepare CDs-based RTP materials and solve the problem of CDs luminescence quenching in the solid-state, the current effective method is to stabilize triple states (T 1 ) , suppress the nonradiative transitions, and limit vibrations and rotations of molecules by embedding CDs into appropriate substrates with the help of hydrogen bonds. [14][15][16][17] The phosphorescence phenomenon in the CDsbased composite system has attracted more and more attention in recent years. [14][15][16][18][19][20][21] Gou et al. reported a series of RTP composites based on tunable polyaniline CDs (PACDs) and polymer matrices (polyacrylic acid, polyacrylamide (PAM), polyvinyl alcohol (PVA)). Only green RTP emissions with adjustable lifetime have been realized by the hydrogen bonding formed between polymer matrices and PACDs. [14] Li et al. prepared an efficient CDs-based RTP material by mixing N-doped CDs (NCDs) with urea and biuret through one-pot heating method. The appearance of CN bonds creates new energy level structures. The interaction of the mixture of biuret and NCDs with composite matrices is This is the first report of full-color afterglow composites composed of four multicolored (blue, green, orange, and red) carbon dots (CDs) in polyacrylamide (PAM) matrix. Thus, adjustable four-color room-temperature phosphorescence (RTP) CDs@PAM composites are prepared on a PAM platform. The abundant amide groups in PAM are connected to the functional groups in CDs by hydrogen bonds, which promote the intersystem crossover and inhibit the non-radiative relaxation of triple states (T 1 ) in CDs@PAM and effectively shield the quenching agents such as oxygen. Furthermore, the rigid hydrogen bond mesh structure is beneficial to the stability of T 1 in CDs@PAM. In addition, the results of electron spin resonance reveal that the afterglow of CDs@PAM composites is not caused by oxygen defects and the increase of oxygen defects hinders the emissio...

Raman spectroscopy and several microstructure analysis techniques have been used to better characterize recently synthesized copper‐cysteamine Cu3Cl(SR)2, where R = CH2CH2NH2. Nanoparticles of this new copper‐cysteamine have been identified as having potential applications in radiation detection and cancer treatment because of the fact that they can be activated by light, X‐rays, ultrasound, and microwave radiation to produce reactive oxygen species. Three samples were grown under different conditions, and their microstructure was examined by using Raman spectroscopy, Fourier transform infrared, scanning electron microscopy, energy dispersive X‐ray scattering, and X‐ray diffraction. The Raman spectroscopy and Fourier transform infrared measurements identify numerous Raman active and infrared absorption bonds with wavenumbers ranging from 200 to 3,500 cm−1. Scanning electron microscopy scans show well‐faceted crystals varying in size from approximately 10 nm to 4 μm, energy dispersive X‐ray scattering measurements identify relative elemental composition (C = 48%, N = 37.5%, S = 5%, Cl = 2.6%, Cu = 7%), X‐ray diffraction data show the crystal plane spacing varies from 0.8454 to 0.8616 nm. The microstructure observed for the three samples is consistent with variations in the growth conditions.

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We present computer simulations on the design and performance of a broadband and extremely highly efficient (∼98%) CMOS-compatible metamaterial nanostructure for solar energy applications. An optimized unit cell of the nanostructure consists of a 300 nm × 300 nm × 100 nm titanium nitride (TiN) base covered with 60 nm thick SiO2. A 50 nm high TiN disk of 90 nm radius sits over the SiO2 dielectric. The TiN disk is capped with another disk of HfO2 of 90 nm radius and 30 nm height into which six Au nanoparticles (NPs) are symmetrically placed. A periodic array of such unit cells of 300 nm periodicity covers an underlying solar panel. We investigate the performance of the absorber as functions of wavelength, angle of incidence, and polarization of incident sunlight by utilizing the COMSOL Multiphysics software. We observe an impressive absorption of approximately 98% for normal incidence and the broadband range of wavelengths from 250 nm to 1100 nm. Additionally, the absorption is almost independent of the polarization of light and remains higher than 90% for a wide range of incidence angles.

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