Ke Sun,† Shaohua Shen,*,‡,§ Yongqi Liang, Paul E. Burrows, Samuel S. Mao,* and Deli Wang*,†,⊥,# †Department of Electrical and Computer Engineering, Material Science Program, and QualComm Institute, University of California at San Diego, La Jolla, California 92093, United States ‡International Research Center for Renewable Energy, State Key Lab of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China Department of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720, United States Department of Chemistry, Chemical Biological Center, Umea ̊ University, Linnaeus vag̈, 6 901 87 Umea,̊ Sweden Samuel Mao Institute of New Energy, Science Hall, 1003 Shangbu Road, Shenzhen, 518031, China

Enabling silicon for solar-fuel production

Pyramidal texturing of silicon solar cell with TMAH chemical anisotropic etching

A surface texture enhances the capacity of a solar cell to absorb incident radiation. In high efficiency and industry standard designs alike, pyramidal surface textures play the key role of reducing the reflectance of the cell surface. This reduction is achieved by ensuring that incident light rays suffer at least a double reflection in the various facets of the structure. In this work, we define a general expression for the reflectance of a pyramidal texture by identifying discrete paths of reflection and the fraction of reflected light that follows each of these paths. We apply the expression to analyse the reflection of normally incident light at textured surfaces. We examine three common morphologies, finding that a regular array of inverted pyramids just outperforms a random array of upright pyramids, with a regular array of upright pyramids showing poorer capacity to reduce front surface reflection. We extend the analysis to determine the transmittance of the various structures, thus permitting the calculation of a figure of merit that can be used to optimise the thickness of antireflection coatings (ARCs). Finally, by examining the angles at which light is reflected by the pyramidal textures, we find that an encapsulant of refractive index greater than 1.59 gives between 79 and 92% of the initially reflected light a second chance to enter the solar cell.

Reflection of normally incident light from silicon solar cells with pyramidal texture

Controlling the interface quality and surface microstructure of the cuprous oxide (Cu2O) p–n homojunction is crucial to obtaining high-efficiency film solar cells. However, the low-cost synthetic t...

Photovoltaic Efficiency Enhancement of Cu2O Solar Cells Achieved by Controlling Homojunction Orientation and Surface Microstructure

Improvement on surface texturing of single crystalline silicon for solar cells by saw-damage etching using an acidic solution

An optimized texturing process for silicon solar cell substrates using TMAH

The use of very high frequency (VHF) plasma enhanced chemical vapor deposition in a capacitive discharge is investigated to fabricate hydrogenated amorphous silicon carbon alloys, using silane and methane as silicon and carbon precursors, respectively, and hydrogen dilution of the gas mixture. The properties of samples differ significantly from that is normally observed for rf deposition. A wide band-gap material is obtained, with a carbon ratio ranging from 0.2 to 0.63. An energy gap up to 3.4eV is measured, indicating a large sp3 content. The most interesting properties are observed using 90% hydrogen dilution and 350°C as substrate temperature. In this case, a SiC bond concentration up to 6×1022cm−3 was measured for stoichiometric samples, associated to a highly crosslinked structure and no detectable SiCH3 bending signal. The role of hydrogen in determining the optical properties of the film is established and is shown to affect mainly the valence electron concentration. Based on the free energy mod...

Daniele Iencinella

Papers

An optimized texturing process for silicon solar cell substrates using TMAH

Wide band-gap silicon-carbon alloys deposited by very high frequency plasma enhanced chemical vapor deposition

Influence of the sputtering system's vacuum level on the properties of indium tin oxide films

Thin-film solar cells on commercial ceramic tiles

Silicon heterojunction solar cells with p nanocrystalline thin emitter on monocrystalline substrate