ACS Photonics最新文献

We show that twisted single-ring hollow-core fibers can exhibit strong helical dichroism, i.e., a different transmission depending on the orbital angular momentum of the launched light. Experimentally, we observe loss differences of at least 40 dB/m over a broad spectral range (>60 THz). We investigate the effect via analytical and numerical studies and show that considerably higher differential loss can be achieved over a broader spectral range (>180 THz). Our observation provides new routes for controlling the polarization state, extends previous studies of circularly dichroic waveguides, and has many potential applications, such as the realization of new polarizing elements in previously inaccessible spectral regions, chiral sensing, broadband generation of vortex beams, and optical communication.

Molecular additives are widely used to improve the film quality and optoelectronic performance of solution-processed metal halides, owing to their diverse interactions with metal-halide precursors. However, the relationship between additive-precursor interaction strength and the optoelectronic performance of metal halides remains unclear. In this study, we investigate cesium copper iodide (Cs–Cu–I) light-emitting diodes (LEDs) incorporating crown ether (CE) additives and demonstrate that the additive-Cs⁺ interactions can significantly influence the device performance. By regulating the additive-Cs⁺ interaction strength, we achieve Cs–Cu–I LEDs with a peak external quantum efficiency of 4.5%, over 20 times higher than that of the control device. The remarkable EQE enhancement is primarily attributed to the suitable additive-Cs⁺ interactions, which enable a gradual release of free precursors to participate in the crystallization of Cs–Cu–I, thus improving the crystalline quality of emissive films. This work not only provides valuable insights into the rational design of molecular additives for copper halide LEDs but also offers guidance for other metal halide optoelectronic devices, particularly those involving additive-precursor interactions.

Lead sulfide (PbS) colloidal quantum dots (CQDs) are of great interest for short-wave infrared (SWIR) optoelectronic devices due to their tunable bandgaps across the whole SWIR spectra. PbS CQD inks synthesized directly at room temperature (RT) and ready for the fabrication of various SWIR devices are highly demanded. There are currently no available protocols for RT synthesis of PbS CQDs with absorption beyond 1200 nm. Here, we report on the first synthesis of PbS CQDs at RT with an absorption beyond 1800 nm. There is a delicate balance between nucleation of new seeds and growth of existing dots regulated by the lead-to-sulfur (Pb/S) precursor ratio in the reaction medium, and a proper Pb/S ratio ranging from 1.1 to 2 should be maintained to keep the continuous growth. Photodiodes based on PbS CQDs with a 1550 nm excitonic absorption are fabricated to demonstrate their suitability for device applications. The resulting devices achieve a high photo responsivity of 0.635 A/W, a specific detectivity of 1.01 × 10¹¹ Jones, and a fast response with rise and fall times of 1.08 and 1.10 μs, respectively.

Solar hybrid photovoltaic/thermal (HPT) systems maximize the overall solar energy conversion by simultaneously converting solar energy into electrical and thermal energy. However, the practical implementation of HPT systems is hindered by a lack of suitable optical materials capable of efficiently splitting the incident solar spectrum into the desired photovoltaic (PV) and photothermal (PT) bands. In this work, we provide the first demonstration of a multifunctional asymmetric metal-dielectric-metal (asym-MDM) optical coating to be used in an HPT system. The asym-MDM serves as the dual function of a quad-band spectrum splitter and a thermal receiver, leveraging on the multiorder spectral responses and the lossy nature of nickel. Moreover, silica aerogel is employed as a transparent insulting material to enhance the thermal storage capability, while the heat is effectively utilized for increasing the temperature difference of a thermoelectric generator (TEG). As a result, a simple and highly compact HPT system is developed, with simultaneous extraordinary heat mitigation of the single-junction amorphous silicon solar cell and heat generation at the hot side of the TEG. This leads to 63.9 and 370% performance improvements for the PV and PT subsystems at a solar concentration of 3, respectively. Asym-MDM will provide a low-cost yet high-efficiency solution for application of an HPT system in solar energy harnessing.