Quantitative measurement and design of texture morphology for high-efficiency thin-film silicon solar cells

Abstract

To decouple the trade-off relationship between short-circuit current I SC and open-circuit voltage V OC of thin-film silicon solar cells, which vary with texture morphology, it is necessary to first clarify the relationship between a solar cell's properties and its texture morphology. We have developed a method for quantitatively measuring the texture morphology, which has enabled us to identify novel indices on the basis of texture width and angle individually correlated to I SC and V OC . A texturing process based on these indices should allow I SC and V OC to be improved independently.

Textured Stainless Steel as a Platform for Black Mg2Si/Si Heterojunction Solar Cells with Advanced Photovoltaic Performance

“…The resulting texture morphology was investigated by atomic force (AFM, Solver P47, NT-MDT, Moscow, Russia) and scanning electron (SEM, Hitachi S3400, Tokyo, Japan) microscopy, while optical properties were measured on a spectrophotometer with an integrating sphere (Cary 5000, Varian, Palo Alto, CA, USA) under normal incident conditions. While surface roughness (RMS) was directly available from AFM data, several key parameters were missing, which could have helped to achieve a trade-off between SC short-circuit current and open-circuit voltage that depends on the texture’s morphology, rather than simply on its RMS value [ 35 ]. Thus, for correlating morphology and optical properties, we used texture angle calculations derived from surface topography images, with calculation details being available elsewhere [ 36 ].…”

“…First, a 100-nm-thick magnesium (Mg) film was deposited at room temperature with a 25 nm/min evaporation rate from K-cell, followed by annealing at 350 °C for 5 min. This procedure has previously been shown to result in silicidation of Si surface texture and black Mg 2 Si formation [ 35 ]; this step is shown in Figure 1 a, while the optical photograph of the produced sample marked as b-SS/Fe 3 O 4 /Si/Mg 2 Si is shown in Figure 1 b. At the final fabrication stage (see Figure 1 a), a bilayer of Si and Ca (K-cell, 25 nm/min) was deposited atop the Mg 2 Si light absorbing layer at room temperature followed by rapid thermal annealing at 600 °C for CaSi 2 formation [ 36 ].…”

Use of microcrystallinity depth profiling in an actual tandem silicon solar cell by polishing to achieve high conversion efficiency

“…[2][3][4] This was achieved by improving the µc-Si:H quality and device structure, including optical confinement. 5,6) Recently, École Polytechnique Fédérale de Lausanne has developed thin-film silicon solar cells with 12.63% efficiency. 7) In addition, Kaneka also developed highefficiency triple-junction solar cells with 13.4% efficiency with a p-i-n configuration.…”

“…On the other hand, to enhance the optical confinement effect, the shape of TCO tends to be more complex. Conversely, the more complex the shape of TCO, the more difficult it is to attain a stable quality of µc-Si:H. 5) Regarding the tin oxide (SnO 2 ) as the TCO, it is pyramidal in shape. Its angles in the region of the valley are sharp.…”

Analytical investigation of SiGe solar cell including texture morphology effects

“…In this context, the optical confinement is an important parameter for enhancing the efficiency of solar cells. F Transparent conductive oxides (TCOs) with randomly textured surfaces are widely used to improve optical confinement [5][6][7][8]. On the other hand, the surface texture affects the electrical performance for the reason that it influences the quality of the SiGe layer and the optical trapping at the surface.…”