Solar cells from 120 PPMA carbon-contaminated feedstock without significantly higher reverse current or shunt

In a bid to drive down the cost of silicon wafers, several options for solar grade silicon feedstock have been investigated over the years. All methods have in common that the resulting silicon contains higher levels of impurities like dopants, oxygen, carbon or transition metals, the type and level of impurities depending on the raw materials...

Differences in reverse bias voltage behavior of n-type and p-type multicrystalline solar cells

The use of n-type, instead of p-type, silicon wafers for the production of mc-Si solar cells has a clear effect on the pre-breakdown behavior under reverse bias conditions. In p-type solar cells, material related breakdown patterns that are commonly observed in luminescence and thermography images. These patterns do not appear in the...

Effect of Al contact pitch on rear passivated solar cells

In search of solar cell concepts that allow processing of thinner wafers (<150 ?ѭ), the conventional full Al rear side of p-type solar cells is replaced by an open rear metallization combined with a dielectric passivation layer. We estimate that this modification to the cell concept could result in a gain of 0.3-0.4% in absolute...

Industrial application of uncapped Al2O3 and firing-through Al-BSF in open rear passivated solar cells

Current bottlenecks for industrial application of Al2O3 deposited by Atomic Layer Deposition (ALD) on open rear passivated solar cells are low growth rate, firing stability of thin and uncapped layers, and Firing-through BSF formation during co-firing. Long term stability results on the performance of a high throughput ALD proto-type, the...

Excellent rear side passivation on multi-crystalline silicon solar cells with 20 nm uncapped Al2O3 layer: industrialization of ALD for solar cell applications

Current bottlenecks for industrialization of Al2O3 deposited by Atomic Layer Deposition (ALD) for crystalline silicon solar cell applications are low growth rate and stability of thin and uncapped layers during co-firing. First results on the performance of a high throughput ALD proto-type, the Levitrack, are presented. Excellent passivation...

Parasitic shunt losses in all-side SiNx passivated mc-Si solar cell

In search of solar cell concepts that allow processing thinner wafers (<150 micron), the conventional full Al rear side is replaced by an open rear metallization combined with a dielectric passivation layer. We show a gain of 2.1% (relative) in the product of J?Ƴc?Voc, when we apply a passivated SiNx dielectric layer and local Al contacts...

Stable and efficient p-type multicrystalline silicon cells containing 20 PPMA interstitial oxygen

Interstitial oxygen is the most prevalent impurity in crystalline silicon. An upper limit of around 12 ppma [Oi] has long been accepted for multicrystalline solar cells. This paper demonstrates that it is possible to manufacture solar cells with an efficiency of over 15.4% at 20 ppma interstitial oxygen from commercial multicrystalline p-type...

Internal gettering of iron and chromium to improve multicrystalline silicon wafers

Metallic impurities in interstitial form are one of the most important limiting factors for minority carrier lifetimes in p-type silicon. Interstitial impurities can be transformed into less harmful precipitates by annealing. In this way, it is shown that the minority carrier lifetime can be increased with one order of magnitude for iron and...

Kristallijn silicium zonnecellen: thermische behandelingen en nieuwe materialen - THERMAT II

The TherMat II project investigated the relation between silicon materialquality and solar cell efficiency, and the changes in material which occur as a result of high-temperature process steps. Goals of the project were 1. to find out whether the negative effects of extra impurities in the silicon wafer, e.g. due to the use of new feedstock,...