ABSTRACT
Substitution of monocrystalline or polycrystalline silicon as active materials in photovoltaics with highly efficient perovskite materials is quite common. Although perovskite materials offer better flexibility, are cost-effective, and have higher conversion efficiency, they still require structural modifications for better performance. This study quantitatively investigates how mesoporous top surfaces improve the performance of methylammonium lead iodide (C H 3 N H 3 P b I 3) perovskite solar cells. In fact, both the diameter and the depth of the pores have been tuned to achieve better performance. The performance is further optimized by replacing mesoporous active material with planar active material coated with mesoporous indium tin oxide (ITO). We have demonstrated that the proposed structure achieves the maximum conversion efficiency (η) of 27.43% with an open-circuit voltage (V O C ) of 1.07 V and a short circuit current density (J S C ) of 29.09m A/c m 2, with a fill factor (FF) of 88.10%.
ABSTRACT
Enhancement of optical to electrical conversion is vital for improving the efficiency of any solar cell. In recent years, use of thin films instead of bulk wafers has resulted in a huge reduction of production cost, and as such, efficiency enhancement of thin-film solar cells is considered in this study. Though this enhancement depends on several factors, most significant among them is the increase in light absorption within the active material of the solar cell. In this work, various types of grating structures on both sides of active solar cell material for light trapping are studied in detail, and a new type of arrangement of optimized grating structure that significantly improves the light absorption is selected. Enhancement of light absorption for change in dielectric material of the grating structure without changing the active material is also observed. Along with structural optimization, simulated electrical characterization of the samples was also performed, which yields a short-circuit current density of 29.27mA/cm2 with conversion efficiency of 14.51%, having a fill factor of 0.83 for a typical ultrathin layer of active material of thickness 2 µm. This is quite significant because typical cells of this category have much lesser conversion efficiency.
ABSTRACT
The characterization of imaging methods as three-dimensional (3D) linear filtering operations provides a useful way to compare the 3D performance of optical surface topography measuring instruments, such as coherence scanning interferometry, confocal and structured light microscopy. In this way, the imaging system is defined in terms of the point spread function in the space domain or equivalently by the transfer function in the spatial frequency domain. The derivation of these characteristics usually involves making the Born approximation, which is strictly only applicable to weakly scattering objects; however, for the case of surface scattering, the system is linear if multiple scattering is assumed to be negligible and the Kirchhoff approximation is assumed. A difference between the filter characteristics derived in each case is found. However this paper discusses these differences and explains the equivalence of the two approaches when applied to a weakly scattering object.
