Systematic Investigation of the Optical Characteristics of GaAs Solar Cells with Antireflection Coatings and Metallic Nanoparticles Using Finite Element Analysis

For energy-efficient thin-film solar cells, photovoltaic researchers are investigating alternative strategies like metallic nanostructures supporting plasmon resonance and ultrathin coatings of antireflective materials to minimize optical absorption loss. To reduce the reflection losses from the surface of the solar cells (SCs), optimizing the dimensions of the metallic nanostructures and antireflection coating (ARC) is essential. A systematic step-by-step approach is used to gain scientific insights into improving the planar GaAs SC performance. In this article, device performance optimization of a solar cell was studied with five distinct architectures, namely, planar GaAs, GaAs with metal nanoparticle (MNP) on top, GaAs coated with ARC, GaAs with MNP over ARC, and GaAs with MNP embedded in ARC using the finite element method. To analyze the effect of ARC thickness and MNP size on optical characteristics, the optical short-circuit current density ( J opt ) is computed using absorptance data as the performance parameter. We used various metals on the GaAs/Al architecture to choose MNP materials, and titanium (Ti) nanoparticles were chosen because they have the maximum J opt . For ARC, we have chosen three oxides, Ta 2 O 5, MoO 3, and ZnO, and two polymeric materials, P3HT and PEDOT:PSS. We have compared the optical performance of the different optimized architectures using J opt, absorption spectra, electric field, and photogeneration rate. This exhaustive analysis shows that Ti MNPs with a diameter of 180 nm and P3HT ARC with an 80 nm thickness, placed over GaAs planar structure, deliver maximum J opt values of 29.87 and 27.67 mA/cm 2, respectively. Further, to understand the dual impact of plasmons and ARC, we simultaneously varied the MNP size and the ARC thickness and found that GaAs planar structure coated with 10 nm thick MoO 3 and Ti plasmon with diameter of 160 nm has the best J opt of 29.66 mA/cm 2 . Secondly, we embedded Ti plasmons of 60, 120, and 180 nm diameters into the ARC film and found that MNPs enhance photocurrent. It is observed that Ti MNPs with an optimized diameter of 180 nm embedded in a 40 nm thick MoO 3 ARC and placed directly over the GaAs structure deliver the highest J opt of 30.45 mA/cm 2 . This comprehensive analysis can help researchers to improve the GaAs SC efficiency using the combined effect of geometrically optimized ARCs and MNPs.