Effect of Subgrains on the Performance of Mono-Like Crystalline Silicon Solar Cells

Abstract

The application of Czochralski (Cz) monocrystalline silicon material in solar cells is limited by its high cost and serious light-induced degradation. The use of cast multicrystalline silicon is also hindered by its high dislocation densities and high surface reflectance after texturing. Mono-like crystalline silicon is a promising material because it has the advantages of both mono- and multicrystalline silicon. However, when mono-like wafers are made into cells, the efficiencies of a batch of wafers often fluctuate within a wide range of >1% (absolute). In this work, mono-like wafers are classified by a simple process and fabricated into laser doping selective emitter cells. The effect and mechanism of subgrains on the performance of mono-like crystalline silicon solar cells are studied. The results show that the efficiency of mono-like crystalline silicon solar cells significantly depends on material defects that appear as subgrains on an alkaline textured surface. These subgrains have an almost negligible effect on the optical performance, shunt resistance, and junction recombination but significantly affect the minority carrier diffusion length and quantum efficiency within a long wavelength range. Finally, an average efficiency of 18.2% is achieved on wafers with hardly any subgrain but with a small-grain band.

Growth and Defects in Cast‐Mono Silicon for Solar Cells: A Review

“…[36] Sub-GBs, though with a small deviation of crystalline lattice orientation, usually cause distorted regions [13,21] which could attract impurity precipitating and result in dislocation generation, significantly decreasing the minority carrier lifetime because of their strong recombination activity. [37][38][39] Lantreibecq et al [40] observed sub-GBs with TEM and SEM. They found that sub-GBs were constituted by a set of dense, perfectly organized immobile dislocations aligned along the growing direction and having an edge character.…”

Impact of Solar Panel Orientation on the Integration of Solar Energy in Low-Voltage Distribution Grids

“…Other differences include taking the effects of wind speeds on solar module cooling into account, as well as the light-induced degradation (LID) phenomenon. LID is the additional long-term degradation of solar cell performance when exposed to light, especially pronounced in monocrystalline solar cells [29]. Because it varies wildly with the quality of the solar cell silicon, we choose not to model this behaviour in the presented model.…”

Investigation of subgrains in directionally solidified cast mono-seeded silicon and their interactions with twin boundaries

“…Subgrains are observed in all silicon ingots that are produced by casting processes for PV applications: in cast mono (cm-Si) [4][5][6], high-performance multicrystalline (HPmc-Si), [7] and conventional multicrystalline (mc-Si) silicon [8]. For mc-Si, either grains with <110> or <111> growth directions were reported to have the highest dislocation density [8][9][10].…”