Light trapping concepts for photon management in solar cells

Photon management is a key component in the development of efficient solar cells. Especially light-trapping concepts have a high potential to realize enhanced efficiencies. Here, we give an overview over several light trapping concepts for photon management in solar cells. These include basic as well as advanced light-trapping concepts. The theoretical limits of light path enhancement of the different concepts are given and experimental work on these topics is resented. The potential of 3D photonic crystals is discussed in the context of the corresponding approaches as well

Plasma enhanced atomic layer deposited MoOx emitters for silicon heterojunction solar cells

A method for the deposition of molybdenum oxide MoOx with high growth rates at temperatures below 200 C based on plasma enhanced atomic layer deposition is presented. The stoichiometry of the overstoichiometric MoOx films can be adjusted by the plasma parameters. First results of these layers acting as hole selective contacts in silicon heterojunction solar cells are presented and discusse

Influence of black silicon surfaces on the performance of back-contacted back silicon heterojunction solar cells

The influence of different black silicon (b-Si) front side textures prepared by inductively coupled reactive ion etching (ICP-RIE) on the performance of back-contacted back silicon heterojunction (BCB-SHJ) solar cells is investigated in detail regarding their optical performance, black silicon surface passivation and internal quantum efficiency. Under optimized conditions the effective minority carrier lifetime measured on black silicon surfaces passivated with Al2O3 can be higher than lifetimes measured for the SiO2/SiNx passivation stack used in the reference cells with standard KOH textures. However, to outperform the electrical current of silicon back-contact cells, the black silicon back-contact cell process needs to be optimized with aspect to chemical and thermal stability of the used dielectric layer combination on the cell

Promising plasma textured black silicon at etch temperatures > 0 °C for PV applications

Maskless plasma texturing, as an outstanding method to fabricate highly antireflective silicon surfaces, is optimized at etch temperatures above 0 °C. We achieve excellent optoelectronic properties suitable for silicon solar cell applications

Properties of black silicon obtained at room-temperature by different plasma modes

Black silicon plasma technology begins to be integrated into the process flow of silicon solar cells. However, most of the current technology is used at cryogenic or very low substrate temperatures. Here, the authors investigate the temperature-dependent properties of black silicon prepared by two different plasma etching techniques for black silicon, a pure capacitively coupled process (CCP), and an inductively and capacitively coupled process (ICP+CCP). It turns out that the ICP+CCP process at room-temperature yields black silicon samples with 93% absorption and minority carrier lifetime above 1 ms. The authors show that these optoelectronic properties are comparable to samples obtained at low temperatures

Passivation of different black silicon surfaces by ALD deposited Al 2O3

Optical properties of black silicon (b-Si) can be tailored to minimize reflection losses to less than 0.6 % between 300-1000 nm and to improve the absorption at the silicon band-edge by light-trapping. Recently, metal assisted wet-chemically etched (MACE) b-Si was exploited to fabricate high efficiency (18.2 %) solar cells with surface passivation by thermal SiO2 and recombination velocities (SRV) of 100 cm/s [1]. We compare surface passivation performance of ALD-Al2O3 on different dry and wet etched nanostructures. SRVs 8 cm/s on bifacially black 1 cm p-type Si FZ wafers were measured. This technological advance will enable higher efficiencies for various PV-cell concepts