PV manufacturing has its roots in sophisticated semiconductor fabrication technology and most of the thin-fllm PV manufacturing has its origin in liquid-crystal display manufac­turing. Manufacturing compliance is a necessity for the success of any new PV devices. There are basically five steps from the discovery of a new physical phenomenon to a mass-scale manufactured product: […]

There are basically two challenges concerning the light absorption of Si-NCs. One is to improve the absorption coefficient of the SRD layer by looking for direct-bandgap transitions. Si-NCs with diameters smaller than 3 nm show much higher absorption coef­ficient than those with diameters higher than 3nm [133]. This has been ascribed to the amorphous structure […]

The knowledge of the exact mechanism of the electrical transport in Si-NC based cell is fundamental to proper design of the cell and to optimize its performances. A reduced effective carrier mobility (compared with the bulk silicon) is observed since the Si – NCs are embedded into an insulating matrix. The carrier transport in such […]

Phase separation is the mechanism associated with the formation of Si-NCs in most of the deposition methods. Usually, a thick SRD layer is deposited onto a proper substrate and then annealed. This leads both to a broad size distribution of Si-NCs and to nonuni­form interdot distances. The former will result in a broad absorption spectrum, […]

One promising application of Si-NCs is for the downshifter solar cells [17], when down­shifting is associated with specific luminescence effects of a downshifting layer, which is deposited on top of the solar cell. Van Sark et al. [112] showed theoretically that a 10% increase in the short-circuit current might be expected by using a quantum-dot-embedded […]

Multiple-carrier generation was observed in a MOS cell with the same structure we discussed in Section 10.3.3 but with different active layers, here consisting of a SRO layer with more silicon excess. A superlinear dependence of Isc on the incident light power was observed. This was explained by the presence of the subbandgap interface states […]

Subbandgap photoresponse of Si-NCs was found in a metal-oxide-semiconductor (MOS) device. Potentially this would be the premise to realize intermediate-band solar cells. The cross section of the device is shown schematically in Figure 10.11. The active layer is a single SRO layer, which has been deposited on a p-type Si substrate by plasma-enhanced CVD (PECVD), […]

10.3.1 All-Silicon Tandem Solar Cells Si-NCs are used in all-silicon tandem cells [102, 103]. The idea is to leverage on the bandgap tunability of the Si-NCs. In Figure 10.5, examples of two-cell and three-cell all-silicon tandem solar cell are reported [90]. The theoretical efficiency limits are 42.5% and 47.5% for two-cell and three-cell stacks, respectively […]