Effect of textured silicon pyramids size and chemical polishing on the performance of carrier-selective contact heterojunction solar cells. (1st May 2019)

• Record Type: Journal Article
• Authors: Singh, Krishna; Nayak, Mrutyunjay; Mudgal, Sapna; Singh, Sonpal; Komarala, Vamsi K.
• Is Part Of: Solar energy. Volume 183(2019)
• Page Start: 469
• Page End: 475
• Publication Date: 2019-05-01
• Subjects: Silicon pyramids size -- Chemical polishing -- Surface passivation -- Minority carrier lifetime -- Carrier-selective contacts -- Heterojunction solar cell; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2019.03.059
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Highlights: We investigated silicon pyramids size and its smoothness effect on CSC solar cells. Passivation of differently textured silicon is investigated by MoOx film. Cell with small pyramids size (∼2 µm) has shown efficiency of ∼14.53%. Smoothening is essential for medium/large pyramids (∼5–8 µm) based cells. Cell performance variation explained by interfacial low-barrier shunts. Abstract: Role of textured crystalline silicon pyramids size and chemical polishing (CP) for isotropic etching of pyramid peaks/valleys are investigated from carrier-selective contact silicon heterojunction solar cell performance. With an increase of average pyramids size from 2 to 8 µm, the effective minority carrier lifetimes (τeff ) are reduced from ∼126 to ∼65 µs with molybdenum oxide (MoOx ) surface passivation layers. After the CP treatment, an increase in the τeff is observed for the same respective textures (from ∼154 to ∼99 µs) due to reduction of charge carrier recombination. The solar cell structure of Ag/ITO/MoOx /n-Si/LiFx /Al is fabricated at room temperature. With small pyramids (∼2 µm), the cell has shown the better power conversion efficiency of ∼14.53%, but, after the CP treatment not much efficiency variation is observed. Whereas; the CP treatment is beneficial for medium/large pyramids (∼5–8 µm) based cells, which has enhanced the open-circuit voltage (45–63 mV) after smoothing/rounding of sharp peak/valley surfaces. But, we have observed a reduction in photocurrent due to an increase of light reflection from smoothened pyramid surfaces. Quantum efficiency analysis has provided the better insight with the silicon surface morphology dependent energy conversion. The cells' reverse saturation currents also have analyzed to understand the silicon surface passivation and MoOx /n-Si junction quality. The performance variation of cells is explained by considering low-barrier shunts at the pyramids' peaks/valleys, which influence the junction built-in potential at the depletion region.