High-Efficiency Hexagonal Nanowire MAPbI3 Perovskite Solar Cell with Broadband Light Trapping

TL;DR

This work addresses the need for high-efficiency, broadband, and polarization-insensitive perovskite solar cells by proposing a hexagonal nanowire MAPbI3 architecture that exploits Mie resonances and Fabry-Pérot cavities. Coupled optical (FDTD) and electrical (drift-diffusion-Poisson) simulations demonstrate strong light confinement and near-complete absorption in the visible range, achieving a predicted PCE of $24.2\%$ with a short-circuit current density of $J_{sc}\approx 27{-}29\ \mathrm{mA/cm^2}$ under AM1.5G illumination. The inclusion of a partially embedded dielectric SiO$_2$ sphere in the ITO layer further elevates the optical Jsc to $29.53\ \mathrm{mA/cm^2}$ by enabling enhanced light coupling and near-field confinement, with the optimized device showing an effective Voc around $1.02\ \mathrm{V}$ and FF ~0.85. These results highlight the potential of integrating nanoscale geometry-driven photonic confinement with conventional charge-transport layers to realize scalable, high-performance PSCs for thin-film photovoltaics.

Abstract

Perovskite solar cells (PSCs) have emerged as strong contenders for the next generation of photovoltaic (PV) technologies due to their exceptional light absorption properties, tunability, and affordability in manufacturing. Here, we presented an ingenious hexagonal nanowire (HNW)-based PSC that achieves broadband absorption, minimizes reflectance, and offers robust polarization insensitivity by improving light-matter interaction and increasing charge-collection efficiency. The rotational symmetry of the HNW configuration yielded polarization-independent absorbance under both TE and TM illumination across the visible and near-infrared spectra. The optimization of the geometrical parameters of CH3NH3PbI3-based HNW structure, including diameter, period, and fill ratio, offered a wide rangeof variations that influenced both optical properties and device performance. To further intensify photon confinement, a dielectric SiO2 sphere is partially embedded in the ITO layer, improving long-wavelength absorbance and increasing electron-hole pair generation near the active region. We analyzed the finite-difference time-domain (FDTD) method to examine the optical properties of our proposed structure. This study demonstrates that our proposed structure has achieved a higher generation rate, enhanced absorbance, and a higher optical short-circuit current density (Jsc) of 29.53 mA/cm2. Electrical performance is assessed by solving the coupled drift-diffusion and Poisson equations for the dynamics of carrier transport. The optimized HNW structure achieved a notable power conversion efficiency of 24.2%, highlighting a strong connection between optical confinement and effective carrier transport. These attributes render the proposed HNW PSC a viable option for high-performance PV systems and scalable thin-film solar technologies.

Figures (9)

• Figure 1: (a) Schematics of the unit cell of an HNW-based nanostructured PSC, (b) including a SiO$_2$ based sphere on top of the ITO, (c) inserting the sphere inside the ITO, (d) cross-sectional view of the xz plane of our proposed structure with simulation setup.
• Figure 2: (a) Absorbance spectra for different radius at a fixed FR of 0.5, (b) optical $J_{\text{sc}}$ for different radius at FR = 0.5, (c) optical $J_{\text{sc}}$ for a fixed radius of 150 nm for varying FR, (d) absorbance, reflectance, and transmittance spectra for FR = 0.9 at a radius of 150 nm.
• Figure 3: Optical $J_{\text{sc}}$ values (a) SiO2 sphere on ITO layer, (b) SiO2 sphere partially embedded into the ITO layer.
• Figure 4: (a) Absorbance spectral density for three different configurations of the optimized structure. The inset shows the variation of absorbance spectra for the three configurations, (b) absorbance, reflectance, and transmittance spectra for the configuration of penetrating the sphere into the ITO layer, (c) $J_{\text{sc}}$ values for these three different configurations (d) percentage (%) improvement in $J_{\text{sc}}$.
• Figure 5: Generation profile for our proposed structure: (a) without sphere, (b) sphere on top of ITO layer, (c) sphere inside the ITO layer.