Multicrystalline Silicon Thin‐Film Solar Cells Based on Vanadium Oxide Heterojunction and Laser‐Doped Contacts

Abstract

Liquid phase crystallized (LPC) silicon thin films on glass substrates are a feasible alternative to conventional crystalline silicon (c‐Si) wafers for solar cells. Due to substrate limitation, a low‐temperature technology is needed for solar cell fabrication. While silicon heterojunction is typically used, herein, the combination of vanadium oxide/c‐Si heterojunction as emitter and base contacts defined by IR laser processing of phosphorus‐doped amorphous silicon carbide stacks is explored. LPC solar cells are fabricated using such technologies to identify their issues and advantages with a promising performance of an active‐area efficiency of 5.6%. Apart from the absence of light‐trapping techniques, the relatively low efficiency obtained is attributed to a low lifetime in the LPC silicon bulk. These poor material properties imply a short diffusion length that makes it that only photogenerated carriers in the emitter regions can be collected. Consequently, future devices should show narrower base contact regions, suggesting a shorter‐wavelength laser, combined with longer LPC substrate lifetimes.

Multicrystalline, Highly Oriented Thick‐Film Silicon from Reduction of Soda‐Lime Glass

“…Thus, the expected diffusion lengths are close to or exceed the CSS layer thickness several times. [12,17] Furthermore, the net carrier concentration profile in Figure 5 (inset) indicates a pp + doping structure of the silicon layer corresponding to an absorber with back-surface field (BSF) beneficial for blocking minority carriers (electrons) from the AlO x bottom contact.…”

“…[16] A low-temperature technology of vanadium oxide/c-Si heterojunctions defined by IR laser processing was proposed for emitter and base contact formation. [17] Replacing technical glass as a substrate of mc-silicon solar cells with soda-lime glass is the next logical step for further cost reduction. Correspondingly, LPC on soda-lime glass for photovoltaics (PV) was recently reported, however, with a considerably lower PV efficiency of 4.3%.…”

“…[ 16 ] A low‐temperature technology of vanadium oxide/c‐Si heterojunctions defined by IR laser processing was proposed for emitter and base contact formation. [ 17 ]…”

Diode Laser‐Crystallization for the Formation of Passivating Contacts for Solar Cells

“…[4] These were used in the recent past of amorphous Si for the crystallization for thin-film solar cells on glass. [5][6][7][8]…”

Secondary Ion Mass Spectrometry Study of Hydrogenated Amorphous Silicon Layer Disintegration upon Rapid (Laser) Annealing

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We regret to inform our readers that Dr. Wolfhard Beyer has passed away during the review process of this publication.

IntroductionHydrogenated amorphous silicon (a-Si:H) films are widely used and are of interest for various technologies like thin film solar cells, [1][2][3] silicon heterojunction solar cells, [4][5][6] thin film silicon solar cells on glass, [7][8][9] as well as transistors in large area displays. [10] Hydrogen plays a crucial role in these devices as it passivates silicon defects.

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