Numerical Approach to the Plasmonic Enhancement of Cs2AgBiBr6 Perovskite-Based Solar Cell by Embedding Metallic Nanosphere.

Lead-free Cs2AgBiBr6 perovskites have emerged as a promising, non-toxic, and eco-friendly photovoltaic material with high structural stability and a long lifetime of carrier recombination. However, the poor-light harvesting capability of lead-free Cs2AgBiBr6 perovskites due to the large indirect band gap is a critical factor restricting the improvement of its power conversion efficiency, and little information is available about it. Therefore, this study focused on the plasmonic approach, embedded metallic nanospheres in Cs2AgBiBr6 perovskite solar cells, and quantitatively investigated their light-harvesting capability via finite-difference time-domain method. Gold and palladium were selected as metallic nanospheres and embedded in a 600 nm thick-Cs2AgBiBr6 perovskite layer-based solar cell. Performances, including short-circuit current density, were calculated by tuning the radius of metallic nanospheres. Compared to the reference devices with a short-circuit current density of 14.23 mA/cm2, when a gold metallic nanosphere with a radius of 140 nm was embedded, the maximum current density was improved by about 1.6 times to 22.8 mA/cm2. On the other hand, when a palladium metallic nanosphere with the same radius was embedded, the maximum current density was improved by about 1.8 times to 25.8 mA/cm2.

Numerical Study on Overcoming the Light-Harvesting Limitation of Lead-Free Cs2AgBiBr6 Double Perovskite Solar Cell Using Moth-Eye Broadband Antireflection Layer.

Lead-free Cs2AgBiBr6 double perovskite has emerged as a promising new-generation photovoltaic, due to its non-toxicity, long carrier lifetime, and low exciton binding energies. However, the low power conversion efficiency, due to the high indirect bandgap (≈2 eV), is a challenge that must be overcome and acts as an obstacle to commercialization. Herein, to overcome the limitations through the light trapping strategy, we analyzed the performance evaluation via FDTD simulation when applying the moth-eye broadband antireflection (AR) layer on top of a Cs2AgBiBr6 double perovskite cell. A parabola cone structure was used as a moth-eye AR layer, and an Al2O3 (n: 1.77), MgF2 (n: 1.38), SiO2 (n: 1.46), and ZnO (n: 1.9) were selected as investigation targets. The simulation was performed assuming that the IQE was 100% and when the heights of Al2O3, MgF2, SiO2, and ZnO were 500, 350, 250, and 450 nm, which are the optimal conditions, respectively, the maximum short-circuit current density improved 41, 46, 11.7, and 15%, respectively, compared to the reference cell. This study is meaningful and innovative in analyzing how the refractive index of a moth-eye antireflection layer affects the light trapping within the cell under broadband illumination until the NIR region.

Improving of Sensitivity of PbS Quantum Dot Based SWIR Photodetector Using P3HT.

In this study, we improved the photosensitivity of the lead sulfide quantum dot (PbS QD)-based shortwave infrared (SWIR: 1.0-2.5 µm) photodetector by blending poly(3-hexylthiophene-2,5-diyl) (P3HT) with PbS QD. The PbS QD used for SWIR photoactive layer showed an absorption peak at 1410 nm. In addition, by using zinc oxide nanoparticles (ZnO NPs) as an interlayer, we obtained the stable current characteristics of our device. To confirm the effectiveness of P3HT on the PbS QD-based SWIR photodetector, we compared the electrical characteristics of a PbS QD-based device with a hybrid P3HT:PbS QD-based device. In the reverse bias region, the current on/off ratio of the PbS QD-based device was 1.3, whereas the on/off ratio of the hybrid P3HT:PbS QD-based device was 2.9; 2.2 times higher than the PbS QD-based device. At -1 V, the on/off ratio of the PbS QD-based device was 1.3 and the on/off ratio of the hybrid P3HT:PbS QD-based device was 3.4; 2.6 times higher than the PbS QD-based device. The fabricated P3HT:PbS QD-based device had the highest on/off ratio when -1 V voltage was applied.