Crystalline silicon on glass—interface passivation and absorber material quality

Abstract

Thin crystalline silicon solar cells prepared directly on glass substrates by means of liquid-phase crystallization of the absorber utilize only a small fraction of the silicon material used by standard wafer-based silicon solar cells. The material consists of large crystal grains of up to square centimeter area and results in solar cells with open-circuit voltages of 650 mV, which is comparable with results achieved with multi-crystalline silicon wafers. We give a brief status update and present new results on the electronic interface and bulk properties. The interrelation between surface passivation and additional hydrogen plasma passivation is investigated for p-type and n-type absorbers with different doping concentrations. Internal quantum efficiency measurements from both sides on bifacial solar cells are used to extract the bulk-diffusion length and surface-recombination velocity. Finally, we compare various types of solar cell devices based on 10 μm thin crystalline silicon, where conversion efficiencies of 11-12% were achieved with p-type and n-type liquid-phase crystallized absorbers on glass.

Interface passivation of liquid‐phase crystallized silicon on glass studied with high‐frequency capacitance–voltage measurements

“…Further details about the interlayer and absorber preparation for LPC‐Si solar cells on glass are described in Refs. .…”

“…Single junction thin film silicon solar cells on glass with conversion efficiencies of up to 12% can be achieved by melting the 5–20 μm thick silicon absorbers with a heat source such as a laser or an electron beam . The silicon converts into highly crystalline material which leads to solar cells with open circuit voltages of 618 mV for p‐type absorbers and 657 mV for n‐type absorbers . These liquid‐phase crystallized silicon (LPC‐Si) solar cells on glass are a promising solar cell technology, which combines the advantages of thin film and wafer‐based solar cells, i.e., low material consumption due to thin absorbers and high efficiency potential, respectively .…”

Influence of the Frontside Charge Inversion Layer on the Minority Carrier Collection in Backside Contacted Liquid Phase Crystallized Silicon on Glass Solar Cells

“…Liquid phase crystallized silicon (LPC‐Si) on glass consists of a glass substrate, an interlayer stack and a 5–40 μm Si absorber, which is crystallized over a liquid phase by melting a silicon precursor layer with a line shaped energy source . The interlayer stack serves as diffusion barrier, anti‐reflection coating and passivation layer and is usually composed of silicon oxide (SiO x ), silicon nitride (SiN x ), and/or silicon oxynitride (SiO x N y ) layers . The resulting LPC‐Si layer has an average grain size comparable to that of multi‐crystalline wafers .…”

Interface Engineering for Liquid‐Phase Crystallized‐Silicon Solar Cells on Glass

“…Furthermore, they function as anti‐reflection coating when illuminating the cell in superstrate configuration and as passivation layer of the buried silicon absorber surface towards the glass substrate. So far, silicon oxide (abbreviated as SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y ), silicon carbide (SiC x ), and aluminium oxide (Al 3 O 2 ) were used as interlayer material in LPC‐Si solar cells . The combination of these materials in multi‐layer stacks such as SiO x /SiN x /SiO x (O/N/O) or SiN x /SiO x /SiO x N y (N/O/ON) resulted in efficiencies of more than 13% (Figure ).…”

“…Up to now, prolonged annealing procedures were needed to achieve the necessary hydrogen content in PECVD‐deposited interlayers to prevent delamination during crystallization . However, this step increases manufacturing time and prohibits integrated processing without extended vacuum breaks.…”