Journal ArticleOptoelectronic optimization of graded-bandgap thin-film AlGaAs solar cells. Part II: optimal antireflection front-surface texturingAhmad, Faiz; Monk, Peter B; Lakhtakia, Akhlesh<p>In Part I [<mixed-citation publication-type='journal'><source>Appl. Opt.</source><volume>59</volume>,<fpage>1018</fpage>(<year>2020</year>).<pub-id pub-id-type='coden'>APOPAI</pub-id><issn>0003-6935</issn><pub-id pub-id-type='doi'>10.1364/AO.381246</pub-id></mixed-citation>], we used a coupled optoelectronic model to optimize a thin-film AlGaAs solar cell with a graded-bandgap photon-absorbing layer and a periodically corrugated Ag backreflector combined with localized ohmic Pd–Ge–Au backcontacts, because both strategies help to improve the performance of AlGaAs solar cells. However, the results in Part I were affected by a normalization error, which came to light when we replaced the hybridizable discontinuous Galerkin scheme for electrical computation by the faster finite-difference scheme. Therefore, we re-optimized the solar cells containing an<italic>n</italic>-AlGaAs photon-absorbing layer with either a (i) homogeneous, (ii) linearly graded, or (iii) nonlinearly graded bandgap. Another way to improve the power conversion efficiency is by using a surface antireflection texturing on the wavelength scale, so we also optimized four different types of 1D periodic surface texturing: (i) rectangular, (ii) convex hemi-elliptical, (iii) triangular, and (iv) concave hemi-elliptical. Our new results show that the optimal nonlinear bandgap grading enhances the efficiency by as much as 3.31% when the<italic>n</italic>-AlGaAs layer is 400 nm thick and 1.14% when that layer is 2000 nm thick. A hundredfold concentration of sunlight can enhance the efficiency by a factor of 11.6%. Periodic texturing of the front surface on the scale of 0.5–2 free-space wavelengths provides a small relative enhancement in efficiency over the AlGaAs solar cells with a planar front surface; however, the enhancement is lower when the<italic>n</italic>-AlGaAs layer is thicker.</p>Optica2023-01-0110543712Applied Optics622874871559-128Xhttps://doi.org/10.1364/AO.50003420119961National Science Foundation