Towards high-efficiency Al-BSF c-Si solar cell with both superior omnidirectional and electrical performance by modulating the tilt angle of quasi-periodic inverted pyramid arrays

Seeking efficient light trapping structures with both superior omnidirectional and electrical performance is always on the way for increasing electrical energy output of c -Si solar cell over a wide range of light incident angle (θ). Here, tile angle (δ) of quasi-periodic structure arrays is systematically modulated from 35.9° to 72.8° on diamond-wire-sawn (DWS) c -Si by a simple and cost-effective Cu and Ni co-assisted chemical etching way followed by a post treatment. Interestingly, compared with the conventional micro pyramid (MP), the optimized inverted pyramid (IP) like arrays with a δ of 64° possess both lower light reflectance and carrier recombination, leading to a corresponding solar cell with a higher efficiency (∼19.67%) than that of MP based counterpart (∼19.31%). Moreover, during the increase of θ, the external quantum efficiency (EQE) of 64° IP based cell drops much more slowly than that of MP based one by properly adjusting the relative position of the structure arrays and incident light, indicating its omnidirectional property. Simultaneously, a maximum relative enhancement of electrical output power approaching ∼5.8% in the θ range of −90°–90° is achieved on 64° IP based cell compared to the MP based one, the mechanism behind which is further explained by optical simulation. The above finds pave a new way to increase the electrical energy output in a simple and cost-effective way. • Tilt angle control of quasi-periodic IP was achieved by varying Cu and Ni ratio. • 0.36% absolute increase in solar cell efficiency was made based on 64° IP. • ∼5.8% relative increase of output power was achieved on 64° IP based cell. • Mechanism behind omnidirectional performance was explained by optical simulation.