arXiv subjects

Arpan Sur

Publications and source records attributed to Arpan Sur.

5 recordsLinked to original sources

arXiv2026

Nature-Inspired Hyperuniform Nanohole Patterning for Robust Broadband Absorption Enhancement in Perovskite Solar Cells

Nature-inspired hyperuniform disorder offers a promising route to broadband light trapping in ultrathin perovskite solar cells by avoiding narrowband, illumination-sensitive responses commonly associated with periodic nanophotonic textures. Here, we introduce a nature-inspired ingenious hyperuniform nanohole architecture integrated into the front glass of a planar MAPbI$_3$ perovskite solar cell, serving as a junction-preserving strategy to enhance optical absorption and photovoltaic performance. In comparison with planar and periodic textures, the hyperuniform architecture redistributed incident light across a broader spectrum of in-plane momentum states, strengthened near-interface electromagnetic fields, and improved long-wavelength coupling into the absorber, thereby increasing the effective optical path length without altering the electronically active interfaces. To quantify these effects, we employed a coupled three-dimensional multiphysics framework that integrates finite-difference time-domain (FDTD) optical simulations with drift-diffusion electrical modeling. The optimized design exhibited broadband absorption enhancement, weak polarization dependence, and strong angular tolerance, while suppressing interference-driven spectral oscillations and reducing sensitivity to patterned-layer thickness. Relative to the planar structure, the hyperuniform architecture increased the short-circuit current density from 21.57 to 23.92 mAcm$^{-2}$ and improved the power conversion efficiency from 21.03% to 23.62%, while maintaining $\mathrm{V_{oc}}$ at 1.13 V and preserving a high fill factor of 87.66%. In addition to statistical pattern-invariant performance, stochastic radius-variation analysis indicated a positive enhancement in photocurrent and under fabrication-relevant dimensional disorder.

physics.app-ph↗

arXiv2025

Segmentation-Engineered Ge4Sb6Te7 Switch on SOI Platform for Multilevel Non-Volatile Photonic Neural Inference

Phase-change materials (PCMs) have emerged as key enablers of non-volatile, ultra-compact photonic switches for energy-efficient deep neural network (DNN) applications. In this work, we investigate the recently discovered $\mathrm{Ge_{4}Sb_{6}Te_{7}}$ (GST-467) as a high-contrast optical PCM and demonstrate its suitability for multi-level photonic computing. The complex refractive indices of amorphous and crystalline GST-467 were experimentally extracted and used to propose a segmented silicon-on-insulator photonic switch optimized at 1550 nm. Three-dimensional FDTD simulations reveal that segmentation significantly enhances the extinction ratio while maintaining low insertion loss, resulting in a more than seven times higher design figure of merit than an unsegmented design. Laser-induced thermo-optical simulations further establish efficient, reversible switching with sub-nJ energy requirements for crystallization and amorphization. Compared with established GST, GSST, and GSS compositions, GST-467 provides the largest transmission contrast and supports up to 48 resolvable optical states. When deployed as multi-level weights in photonic DNN architectures, the GST-467 switch achieves superior classification accuracy on EMNIST and Fashion-MNIST benchmarks. These results position GST-467 as a highly promising PCM for scalable, low-energy photonic computing and neuromorphic hardware.

physics.optics↗

arXiv2025

Hierarchically structured, high-efficiency and thermally robust perovskite solar cells with band-engineered double-hole layers

Despite the promising optoelectronic properties of methylammonium lead iodide (MAPbI3)-based perovskite solar cells (PSCs), their commercial viability is hindered by interfacial energy misalignment, suboptimal light absorption, and thermal instability. Here, we present a comprehensive theoretical framework to enhance the power conversion efficiency (PCE) of MAPbI3 based PSC through integrated electronic and morphological engineering. Firstly, to address interfacial recombination and inefficient hole extraction at the perovskite/HTL junction, we introduced a double hole transport layer (HTL) stack comprising CuO and I2O5-doped Spiro-OMeTAD, which significantly improved energy level alignment and carrier selectivity. Comprehensive multiphysics simulations, combining finite-difference time-domain (FDTD) optical analysis with finite element method (FEM) based electrical and thermal modeling, demonstrated that optimized doping concentrations and thickness parameters within the CuO/Spiro-OMeTAD hole transport layers can enhance the PCE to 22.78%. However, planar architectures, while offering ease of fabrication and scalability, exhibit weak near-UV and near-infrared absorption, whereas nanostructures attain superior light trapping but incur significant fabrication complexity, underscoring the need for balanced design strategies. To address these inherent limitations, we propose a hierarchical ellipsoidal patterned solar cell (HEPSC), wherein a top-layer ellipsoidal nanostructure is introduced across the full device stack. This design enhances broadband light trapping and optical confinement throughout the active layers while maintaining fabrication feasibility through geometrically realistic structuring.

physics.optics↗

arXiv2025

Design and Analysis of Plasmonic-Nanorod-Enhanced Lead-Free Inorganic Perovskite/Silicon Heterojunction Tandem Solar Cell Exceeding the Shockley-Queisser Limit

The pursuit of sustainable and highly efficient energy conversion necessitates a transition from toxic and unstable materials to environmentally friendly alternatives. This work presents a simulation-based numerical investigation of a fully inorganic, lead-free tandem solar cell that employs cesium tin-germanium tri-iodide (CsSnGeI3) as the top cell absorber and crystalline silicon (c-Si) as the bottom cell absorber, configured in a silicon heterojunction (SHJ) arrangement. Utilizing CsSnGeI3 as a lead-free perovskite presents a promising solution to the toxicity concerns associated with conventional lead-based perovskites. To further increase near-infrared absorption and reduce the required thickness of the c-Si layer, an ultra-thin gallium antimonide auxiliary absorber is integrated into the SHJ bottom cell. Optical and electrical simulations, conducted using finite-difference time-domain and drift-diffusion modelling, demonstrate that the optimized tandem structure attains a power conversion efficiency of 34.93%, surpassing the Shockley-Queisser limit established for single-junction Si cells. Furthermore, the optimized device showcases an open-circuit voltage of 1.93 V, a short-circuit current density of 21.30 mA/cm2, and a fill factor of 84.74%. Performance is additionally enhanced by incorporating cylindrical gold nanorods within a Si3N4 dielectric medium positioned at the rear of the bottom cell, thus amplifying light absorption through plasmonic effects. Notably, the tandem cell sustains high efficiency even without the plasmonic structure, thereby providing flexibility for cost-effective fabrication. This work underscores the viability of all-inorganic, lead-free tandem cells for next-generation photovoltaics, guided by simulated results that pave the way for high-efficiency, non-toxic solar energy solutions and further experimental validation.

physics.optics↗

arXiv2025

Investigating the Optical and Thermodynamic Properties of 2D MoGe2P4 : Potential Material for Photothermal Therapy

In this study, we analyzed the optical, thermodynamic and electronic properties of 2D MoGe2P4 from the first principle calculation. 2D MoGe2P4 demonstrates superior optical absorption in the NIR-I biological window (750 nm ~ 1000 nm) with a peak near 808 nm and excellent thermal conductivity (63 Wm-1K-1). Finite-difference time-domain (FDTD) simulations and Heat simulations demonstrate that 2D MoGe2P4 possesses efficient photothermal conversion under low laser power (0.5 W/cm2) which is operated in 808nm. Theoretical investigation demonstrates, rapid temperature elevation ({\Delta}T = 24.8 {\deg}C) of the 2D MoGe2P4 within two minutes and photothermal stability over multiple laser cycles, achieving temperatures suitable for effective photothermal therapeutic applications. Photothermal therapy (PTT) is an emerging tumor treatment technique that utilizes photothermal agents (PTAs) to convert near-infrared (NIR) light into localized heat for tumor ablation. To enhance biocompatibility, we analyzed the PEGylation of 2D MoGe2P4 nanosheets through molecular dynamics simulation. PEGylation at human body temperature was stable which signifies 2D MoGe2P4's prospect in therapeutic applications. This research highlights the potential of 2D MoGe2P4 as an emerging material for PTA, establishing a foundation for experimental and clinical trials.

cond-mat.mtrl-sci↗