Lithium batteries that could be charged on exposure to sunlight will bring exciting new energy storage technologies. Here, we report a photorechargeable lithium battery employing nature-derived organic molecules as a photoactive and lithium storage electrode material. By absorbing sunlight of a desired frequency, lithiated tetrakislawsone electrodes generate electron–hole pairs. The holes oxidize the lithiated tetrakislawsone to tetrakislawsone while the generated electrons flow from the tetrakislawsone cathode to the Li metal anode. During electrochemical operation, the observed rise in charging current, specific capacity, and Coulombic efficiency under light irradiation in contrast to the absence of light indicates that the quinone-based organic electrode is acting as both photoactive and lithium storage material. Careful selection of electrode materials with optimal bandgap to absorb the intended frequency of sunlight and functional groups to accept Li-ions reversibly is a key to the progress of solar rechargeable batteries.

Here, we report the comparative study of enhanced second harmonic generation using defect engineering in pyramid-like MoS2 (P-MoS2) flakes to vertically aligned MoS2 (VA-MoS2) flakes. P-MoS2 and VA-MoS2 is synthesized via the modified chemical vapor deposition technique. The second harmonic generation measurements on P-MoS2 and VA-MoS2 are performed by sweeping the excitation wavelength from 1200 nm to 1310 nm in identical conditions. The P-MoS2 flakes show a high SHG signal. The high SHG signal in pyramid-like MoS2 is attributed to the broken inversion symmetry and high thickness of grown MoS2 flakes. VA-MoS2 flakes under the identical conditions show a 34% enhanced SHG signal in comparison to P-MoS2. The midgap states generated due to defects in the form of S vacancies in VA-MoS2 are responsible for this enhancement. These midgap states confine the photons and result in enhanced SHG properties. Our study will pave a new path to understand the role of 2D material morphology in fabricating versatile optical and photonics devices.

No abstract

A systematic optimization study of quantum cascade lasers with integrated nonlinearity for third-harmonic generation is performed. To model current transport the Pauli master equation is solved using a Monte Carlo approach. A multi-objective particle swarm optimization algorithm is applied to obtain the Pareto front. Our theoretical analysis indicates an optimized structure with five orders of magnitude increase in the generated third-harmonic power with respect to the reference design. This striking performance comes with a low threshold current density of about 1.6 kA/cm2 and is attributed to double resonant phonon scattering assisted extraction and injection scheme of the laser.

We fabricated a full-dielectric three-dimensional photonic-crystal cavity containing an ultrahigh-mobility two-dimensional electron gas. By applying a strong perpendicular magnetic field, we created Landau polaritons originating from the ultrastrong coupling of electrons with cavity modes.