Optimisation of SiN antireflection coatings for encapsulated and non-encapsulated silicon solar cells with V-groove surface texture. Paper

Mechanical surface structuring offers significant potential with regard to the fabrication of cost-effective, highly efficient single- and multicrystalline Si solar cells. Among these structures, a V-groove surface design plays an important role. Although this texture already reduces the optical reflection losses significantly, an antireflection (AR) coating is required for optimum cell performance. Remote plasma-enhanced chemical vapour deposition (RPECVD) silicon nitride (SiN) films with refractive index n {>=} 2.0 (at 632.8 nm) act as a very good surface passivating AR coating on phosphorus-diffused n{sup +}p Si solar cells and hence are of great interest for the PV industry. Based on the measured optical properties (n, k) of the remote-plasma SiN films fabricated at ISFH, a detailed theoretical and experimental study is performed to determine the optimum SiN AR coating (i.e. refractive index, film thickness) for non-encapsulated and glass-encapsulated Si solar cells featuring a V-groove surface texture. This optimisation considers the fact that the SiN films giving optimum surface passivation (i.e., films with a large refractive index) lead to considerable parasitic light absorption within these films. Hence, for opti-mum cell performance, a trade-off between optical losses and electronic surface recombination losses is deter-mined for both encapsulated and non-encapsulated V-grooved Si solar cells.