arXiv subjects

Dhriti Sundar Ghosh

Publications and source records attributed to Dhriti Sundar Ghosh.

3 recordsLinked to original sources

arXiv2022

Figure-of-merit for Semi-transparent Solar Cells

Semi-transparent Solar Cells (ST-SCs) has emerged as one of the most prominent energy harvesting technology that combines the benefits of light transparency and light-to-electricity conversion. The biggest opportunities for such technologies lie in their integration as windows and skylights within energy-sustainable buildings or combining them with other solar cell technologies in tandem configuration. The performance of ST-SCs is mainly determined by the trade-off between the competing parameters of the capability to convert the incident light into electricity while allowing some parts to transmit providing transparency through the device. Depending on the target application, the selection of ST-SCs is a tricky affair as some devices might offer high efficiency but compromises transparency and vice-versa. On the other way around, this is again not helped by the fact that due to advancements in materials engineering, processing, and characterization, a vastly different combination of efficiency and transparency has been reported by research groups. So, in order to quantify the performance of ST-SCs, we proposed, a figure-of-merit (FoM) which can be used as a tool that can help in analysing and comparing the performance among various ST-SCs. The defined FoM focuses on the power conversion efficiency of the device, bifaciality factor, transmittance in the desired region, and that corresponding to 550 nm wavelength. Additionally, in this work, we have been shown how the proposed FoM can be correlated for tandem and building-integrated photovoltaics applications. Based on these resultant parameters, FoM is calculated and compared for different device architectures available in the literature. The proposed FoM shall serve as a meaningful guiding path to the researchers for the development of advanced ST-SCs.

cond-mat.mtrl-sci↗

arXiv2019

Tunable plasmons in ultrathin metal films

The physics of electrons, photons, and their plasmonic interactions changes greatly when one or more dimensions are reduced down to the nanometer scale. For example, graphene shows unique electrical, optical, and plasmonic properties, which are tunable through gating or chemical doping. Similarly, ultrathin metal films (UTMFs) down to atomic thickness can possess new quantum optical effects, peculiar dielectric properties, and predicted strong plasmons. However, truly two-dimensional plasmonics in metals has so far elusive because of the difficulty in producing large areas of sufficiently thin continuous films. Thanks to a deposition technique that allows percolation even at 1 nm thickness, we demonstrate plasmons in few-nanometer gold UTMFs, with clear evidence of new dispersion regimes and large electrical tunability. Resonance peaks at 1.5-5 micrometer wavelengths are shifted by hundreds of nanometers and amplitude-modulated by tens of per cent through gating using relatively low voltages. The results suggest ways to use metals in plasmonic applications, such as electro-optic modulation, bio-sensing, and smart windows.

cond-mat.mes-hall↗

arXiv2016

A novel high-contrast imaging technique based on optical tunneling to search for faint companions around bright stars at the limit of diffraction

We present a novel application of optical tunneling in the context of high-angular resolution, high-contrast techniques with the aim of improving direct imaging capabilities of faint companions in the vicinity of bright stars. In contrast to existing techniques like coronagraphy, we apply well-established techniques from integrated optics to exclusively extinct a very narrow angular direction coming from the sky. This extinction is achieved in the pupil plane and does not suffer from diffraction pattern residuals. We give a comprehensive presentation of the underlying theory as well as first laboratory results.

astro-ph.IM↗