ACS Photonics最新文献

In this work, we present a free-space transmissive light amplitude modulator based on thin-film lithium niobate on an insulator platform with an indium tin oxide meta-grating. The design leverages guided mode resonances induced by the transparent conductive oxide layer, enabling efficient electrooptical modulation in the near-infrared region. By integrating transparent conductive oxide both as electrical contact and as the resonating structure, the device eliminates the need for complex alignment during fabrication and minimizes optical losses associated with metallic contacts. We experimentally demonstrate that the device achieves a fundamental mode resonance at 968.5 nm with a quality factor of 440. The electrooptical tuning efficiency is thoroughly investigated across different modes using measurements and simulations. A notable resonance shift of 0.38 nm is observed for the fundamental mode under a ±10 V bias, while a maximum modulation amplitude of 4.6% is achieved with a higher-order mode. Furthermore, the device exploits incident angle tuning as an additional degree of freedom, effectively splitting and sensitively shifting resonances. The new resonances can provide electrooptic tunability. These results highlight the potential of this compact and scalable design for applications in spatial light modulation, optical communications, and tunable optics.

The buried interface between the electron transport layer and the perovskite layer suffers from severe interface defects and imperfect energy level alignment. To address this issue, this study employs a multifunctional organic molecule, curcumin, to modify the interface between SnO₂ and the perovskite layer. The curcumin effectively passivates the defects on both sides of the interface, reducing −OH and oxygen vacancy defects on the SnO₂ surface and passivating uncoordinated Pb²⁺ in the perovskite layer. Through density functional theory calculations, it was found that CM modification at the buried interface increased the defect formation energies of deep (V_Pb and Pb_I) and shallow (V_I) defects at the bottom of the perovskite film. This results in a more compatible energy level alignment and lower defect density at the interface, enhancing carrier transport across it. Consequently, the devices based on curcumin achieve an impressive champion power conversion efficiency (PCE) of 24.46%, compared to 22.03% for control devices. The device retains 90.42% of its initial PCE after 1000 h at 25 °C and 50 ± 5% relative humidity. This work demonstrates a green, hydrophobic, and efficient molecular modification method for the buried interface, laying the foundation for the development of high-performance and stable perovskite solar cells.

Enhancing the emissivity of materials in a broadband and omni-directional manner is crucial for thermal management applications. The emissivity of dielectric media is commonly enhanced by utilizing thermal excitation of surface phonon polaritons (SPhPs) and localized surface phonons (LSPhs) supported by these materials. The SPhPs and LSPhs resonantly enhance emissivity at selective wavelengths inside the Reststrahlen band of the material, which usually spans a limited spectral range and can be distant from the wavelength of the peak thermal radiation. Dielectric media can also support Mie resonances, which are not limited to a spectral range and thus can potentially be used for broadband enhancement of emissivity. In this study, we analyze thermal excitation of Mie resonances in individual and arrays of microcuboids of 6H-SiC. Based on this analysis, we design a periodic array of microcuboids for broadband and omni-directional emissivity enhancement. The designed array increases thermal radiation from a flat, unpatterned 6H-SiC substrate at the normal direction from 67 to 91% of a blackbody while demonstrating enhanced emissivity in a wide angular range. The designed array is fabricated using e-beam lithography and reactive ion etching, and the broadband and omni-directional enhancement of emissivity by capitalizing on Mie resonances is experimentally demonstrated. This study shows the potential of Mie resonances for thermal management applications and provides a guide for the design of efficient thermal emitters.