Silicon nitride as antireflection coating to enhance the conversion efficiency of silicon solar cells

Abstract

The aim of this work is to investigate the effect of single and double layer antireflection coating (ARC) on the performance of silicon solar cells. In this regard, various previous works on single and double layer ARCs have been consulted. Silicon nitride (Si 3 N 4) has been used as ARC material because of its varying refractive index (1.8-3.0). Numerical calculations have been performed to obtain the reflectance for single and double layer Si 3 N 4 using the transfer matrix method. Double layer antireflection coating (DLARC) of Si 3 N 4 is found to have significant advantages over single layer antireflection coating (SLARC). Calculated reflectances have been further used in the PC1D simulator as external reflectance files to study the performance of a silicon solar cell. As a result of the simulation, the reflectance is found to reduce from > 30% to < 2% with short circuit current of 3.86 mA/cm 2 and conversion efficiency of 20.22% for DLARC. Results obtained for DLARC were further compared with a reference cell (without ARC), a cell with SLARC, and a cell with zero reflectance on the front surface.

Effect of obliquity of incident light on the performance of silicon solar cells

“…Most solar cells are coated with ARC layers to reduce reflection of light on the front surface of cell [5, 6, 7]. A good ARC is one that improves performance of solar cell by reducing reflection and increasing photocurrent [5, 6]. A set of well-designed ARCs on the front surface reduce the reflectivity on the front surface of cell from 30% down to less than 2% [4, 5].…”

“…Various methods are used to calculate the reflectivity of ARCs such as Fresnel formula, Rouard's method and transfer matrix method (TMM) [6, 10, 11]. But, transfer matrix method is the most commonly used as this relates the tangential components of electric and magnetic fields across the boundary of layers [11, 13].…”

“…2. Si 3 N 4 is used as antireflection coating with refractive index (and thickness) of top layer 1.8 (83.3 nm) and of bottom layer 2.99 (50.2 nm) [6]. Fig.…”

“…A set of well-designed antireflection coating (ARC) can reduce reflection from more than 30% (for bare silicon) down to less than 2% [5, 6]. Solar cells operate in wavelength ranging from 300 – 1200 nm.…”

“…Solar cells operate in wavelength ranging from 300 – 1200 nm. The ARCs containing single layer can be non-reflective only at single wavelength, generally at the mid of visible spectrum whereas ARCs containing double or more layers are effective over the whole visible spectrum [5, 6]. Many works have been reported on the antireflection coating with different materials such as SiNx/SiNx by R. Sharma [6], MgF 2 /SiNx by Dhungel et al.…”