Light-trapping schemes for silicon thin-film solar cells via super-quadratic subwavelength gratings

Lens centering error measurement based on subwavelength grating with power analysis

This study presents a technique for measuring the centering error of a lens. The technique uses power analysis and is highly accurate. The module is designed by a prism that is patterned using a subwavelength grating combined with a reflection-centering system by using the -1st-order rays at 5 mW and 650 nm. The optical axis error is tested and analyzed by the powermeter by using Snell's law and diffractive characteristics. The resolution of the optical-centering error in the system is amplified by a factor of 4 compared with the centering error measuring system based on autocollimation. The technique proposed in this study improves the sensitivity of the instrument and reduces the requirements of the sensor at the end side based on the direction or energy variation of the light.

Cutting sinusoidal gratings to enhance light trapping in thin-film silicon solar cells

A crystalline silicon thin-film solar cell with a three-layer sinusoidal grating structure is studied. The structure has a double-layer antireflection layer, and the three-layer grating is located in the double-layer antireflection layer and the passivation layer, respectively. The related parameters of the grating structure are optimized by scanning using finite-difference time-domain. The optimization results show that cutting the sinusoidal grating structure can significantly improve the light absorption efficiency of the cell for near-infrared light (750-1100 nm), and the enhancement effect is mainly in the transverse electric (TE)-polarized light. This is because the localized surface plasmon resonance and optical waveguide mode under TE-polarized light can be fully excited after the sinusoidal structure is cut. The short-circuit current density (J _{S C} ) of the optimized three-layer sinusoidal grating structure is 19.82m A/c m ², which is 112.43% higher than that of the planar structure with the same parameters and 23.18% higher than that of the uncut sinusoidal grating structure with the same parameters.

Physical Fields Manipulation for High-Performance Perovskite Photovoltaics

With the efforts of researchers from all over the world, metal halide perovskite solar cells (PSCs) have been booming rapidly in recent years. Generally, perovskite films are sensitive to surrounding conditions and will be changed under the action of physical fields, resulting in lattice distortion, degradation, ion migration, and so on. In this review, the progress of physical fields manipulation in PSCs, including the electric field, magnetic field, light field, stress field, and thermal field are reviewed. On this basis, the influences of these fields on PSCs are summarized and prospected. Finally, challenges and prospective research directions on how to make better use of external-fields while minimizing the unnecessary and disruptive impacts on commercial PSCs with high-efficiency and steady output are proposed.

Enhancement in photocurrent by dual-interface period-mismatched rotating rectangle grating-based c-Si solar cells

A dual-interface period-mismatched rotating rectangular grating structure was designed for crystalline silicon thin film solar cells. The relevant parameters of the grating structures were optimized, and the absorption enhancement mechanisms were also explained by optoelectronic simulation analysis. The numerical results show that the rotating rectangular structure can improve the light-trapping performance by coupling light into the c-Si film to excite the waveguide mode and localized surface plasmon resonances. Moreover, it is found that the light-trapping effect of the rear grating rotating structure is better than that of the front grating rotating structure, because the rear interface can better excite localized surface plasmon resonances. The photocurrent density of the dual-interface period-mismatched rotating rectangular grating structure is increased to $18.01\; {\rm mA/cm}^2$, which is 76.05% higher than that of the planar 300 nm thick c-Si structure. The research results provide general guidance for the design of grating structures for thin-film solar cells.

Numerical study of a highly efficient light trapping nanostructure of perovskite solar cell on a textured silicon substrate

In this paper, a nanostructured perovskite solar cell (PSC) on a textured silicon substrate is examined, and its performance is analyzed. First, its configuration and the simulated unit cell are discussed, and its fabrication method is explained. In this proposed structure, poly-dimethylsiloxane (PDMS) is used instead of glass. It is shown that the use of PDMS dramatically reduces the reflection from the cell surface. Furthermore, the light absorption is found to be greatly increased due to the light trapping and plasmonic enhancement of the electric field in the active layer. Then, three different structures, are compared with the main proposed structure in terms of absorption, considering the imperfect fabrication conditions and the characteristics of the built PSC. The findings show that in the worst fabrication conditions considered structure (FCCS), short-circuit current density (Jsc) is 22.28 mA/cm2, which is 27% higher than that of the planar structure with a value of 17.51 mA/cm2. As a result, the efficiencies of these FCCSs are significant as well. In the main proposed structure, the power conversion efficiency (PCE) is observed to be improved by 32%, from 13.86% for the planar structure to 18.29%.