• Energy Research

Abstract High-efficiency silicon solar cells need a textured front surface to reduce reflectance and to improve light trapping. Texturing of monocrystalline silicon is usually done in alkaline solutions. These solutions are cheaper, but are pollutants of silicon technologies. In this paper, we investigate an alternative solution containing tetramethyl ammonium hydroxide ((CH 3 ) 4 NOH, TMAH ). This study shows the influence of different parameters (concentration, agitation, duration and temperature), to obtain uniform and reliable pyramidal texturization on different silicon surfaces (as cut, etched and polished). Under optimized conditions, TMAH-textured surface led to an average weighted reflectance of 13%, without any antireflection coating independent of the initial silicon surface. Unlike potassium hydroxide (KOH) texturing solution, characterization of silicon oxide layer contamination after TMAH texturing process revealed no pollution, and passivation is less affected by TMAH than by KOH texturization.

Abstract High-efficiency silicon solar cells need a textured front surface to reduce reflectance and to improve light trapping. Texturing of monocrystalline silicon is usually done in alkaline solutions. These solutions are cheaper, but are pollutants of silicon technologies. In this paper, we investigate an alternative solution containing tetramethyl ammonium hydroxide ((CH 3 ) 4 NOH, TMAH ). This study shows the influence of different parameters (concentration, agitation, duration and temperature), to obtain uniform and reliable pyramidal texturization on different silicon surfaces (as cut, etched and polished). Under optimized conditions, TMAH-textured surface led to an average weighted reflectance of 13%, without any antireflection coating independent of the initial silicon surface. Unlike potassium hydroxide (KOH) texturing solution, characterization of silicon oxide layer contamination after TMAH texturing process revealed no pollution, and passivation is less affected by TMAH than by KOH texturization.

Electroluminescence allows rapid characterization of an entire photovoltaic solar cell and visualization of defects at the micrometer scale. Here we focus on the optoelectronic properties of silicon interdigitated back contact cells characterized by electroluminescence. The spatially resolved electroluminescence helps us control the quality of interdigitated back contact structures used in silicon bottom subcells in a three-terminal tandem perovskite on silicon solar cell. Local variations in minority carrier diffusion length, surface recombination velocity and, the impact of resistive and optical losses were analyzed by electroluminescence mapping. In addition, we quantify the radiative saturation current density and the radiative open circuit voltage using the electroluminescence spectrum of the cell. This step allows us to accurately assess the performance limits induced in the device due to the non-radiative recombination.

Electroluminescence allows rapid characterization of an entire photovoltaic solar cell and visualization of defects at the micrometer scale. Here we focus on the optoelectronic properties of silicon interdigitated back contact cells characterized by electroluminescence. The spatially resolved electroluminescence helps us control the quality of interdigitated back contact structures used in silicon bottom subcells in a three-terminal tandem perovskite on silicon solar cell. Local variations in minority carrier diffusion length, surface recombination velocity and, the impact of resistive and optical losses were analyzed by electroluminescence mapping. In addition, we quantify the radiative saturation current density and the radiative open circuit voltage using the electroluminescence spectrum of the cell. This step allows us to accurately assess the performance limits induced in the device due to the non-radiative recombination.

We first introduce selected approaches, concepts and technological strategies to control light collection and absorption in photovoltaic ultrathin film cells for both solar and indoor light harvesting. We then illustrate light trapping into photonic crystal structures with examples of structures and devices, including 100nm thick hydrogenated amorphous silicon and 1µm thick crystalline layer solar cells. Finally, we discuss on the interest of photonic crystal structures to enhance non linear optical processes like down conversion for 3rd generation solar cells. International audience

We first introduce selected approaches, concepts and technological strategies to control light collection and absorption in photovoltaic ultrathin film cells for both solar and indoor light harvesting. We then illustrate light trapping into photonic crystal structures with examples of structures and devices, including 100nm thick hydrogenated amorphous silicon and 1µm thick crystalline layer solar cells. Finally, we discuss on the interest of photonic crystal structures to enhance non linear optical processes like down conversion for 3rd generation solar cells. International audience

Electroless deposition of Ag nanoparticles on PECVD SiNx:H dielectric layers is a new straightforward chemical bath process well adapted to the realization of plasmonic solar cells. Depending on the stoichiometry, SiNx:H contains a certain number of Si nanoclusters embedded in the silicon nitride matrix, that act as reducing agents for Ag ions in solution and thus allows the deposition of Ag nanoparticles directly on the surface. We investigate the influence of the layer stoichiometry and deposition parameters on the nucleation and growth of Ag nanoparticles, and show how they can be adjusted to control the nanoparticle size and density. We also demonstrate that this facile metallization process can be extended to PECVD SiOx layers, another dielectric coating of interest in photovoltaics.