Porous silicon antireflection layer for solar cells using metal‐assisted chemical etching

Abstract

Porous silicon antireflection coatings were generated on fully processed screen‐printed monocrystalline silicon solar cells using metal‐assisted chemical etching in HF:H2O2:ethanol. In this method, interaction of the HF acid with the cell front grid contact results in the dissolution of silver nanoparticles which provide the catalytic sites required to initiate porous silicon formation. Control of the etching time and HF concentration was found critical to attain good antireflection proper‐ ties while avoiding front contact degradation. The optimised porous silicon layer reduced the solar cell effective reflectance from 44% to 12% in the spectral range 400–1100 nm and increased the short‐circuit current density by 46%. The solar cell efficiency was raised by 3% absolute. The simplicity of the method makes it promising for cost‐effective reduction of reflection losses in silicon solar cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Porous Silicon Formation by Metal Nanoparticle-Assisted Etching

“…MAE displays little crystallographic dependence and can be performed on crystalline or multicrystalline Si substrates, and the various Si morphologies and nanomicrostructures obtained are promising for photovoltaic applications in several areas: antireflective coating (Yae et al 2003(Yae et al , 2005(Yae et al , 2006Peng et al 2005a, b;Benoit et al 2008;Lu and Barron 2013;Tsujino and Matsumura 2006b;Chaoui et al 2008;Nishioka et al 2008Nishioka et al , 2009Srivastava et al 2010;Cao et al 2011;Kim et al 2011Kim et al , 2012Geng et al 2012;Wang et al 2013b;Li et al 2013a), texturization for multicrystalline wafers (Tsujino and Matsumura 2006a;Waheed et al 2010;Branz et al 2009;Li et al 2012;Wan et al 2008;Koynov et al 2006Koynov et al , 2007Lipiński 2008;Bastide et al 2009;Yuan et al 2009;Lin et al 2010;Toor et al 2011;Oh et al 2012;Srivastava et al 2012;Tang et al 2013;Shi et al 2013a, b;Hsu et al 2012), porous emitter (Hadjersi and Gabouze 2008;Li et al 2013b), advanced solar cells based on cylindrical macropores (Peng et al 2010) or Si nanorods or nanowires (Garnett and Yang 2008), and layer detachment technique to prepare solar cells based on low-quality substrates or on ultrathin Si layers …”

Nanostructure Formation and Passivation of Large‐Area Black Silicon for Solar Cell Applications

“…The most important reason is that the nanoscale textured silicon surface has a gradually varying refractive index, resulting in low reflectivity and a black appearance 1, 7. Various methods have been developed to texture the silicon surface at the nanometer scale, which is usually referred to as making “black silicon.”2, 8–13 Both ultrafast‐laser textured surfaces and reactive‐ion‐etched Si surfaces have very low reflectance across a broad spectrum, but they are not suitable for commercial large‐area “black silicon” solar cells because of their inefficient and complicated fabrication processes.…”

Silicon Quantum Dots for Photovoltaics: A Review

“…Indeed Pi et al who report an increase in efficiency of 0.6% claim that the efficiency improvement observed by Svreck et al may have been due to the improved optical coupling of the light into the cell by Silicon QDs embedded in the spin-on glass at the solar cell surface (Pi et al, 2011). The authors claim that it is the porous nature of the deposited film which could be at the origin of the observed efficiency increase (porous silicon layers are well known as anti-reflecting coating (Chaoui et al, 2008)) rather than a down-conversion effect of silicon QDs. In their paper, Pi et al propose to deposit a silicon QDs based ink at the solar cell surface by spin-coating.…”