Nanostructures in thin film opto-electronics

Substrate and p-layer effects on polymorphous silicon solar cells

“…Figure 5 shows such a comparison including an a-Si:H solar cell with a thin (20 nm) pm-Si:H buffer layer. It is seen that degradation of J SC is negligibly small for the three cells with the initial J SC values controlled by i-layer band gap while most of degradation is caused by a substantial decrease in F F -a common drawback among a-Si:H p-i-n devices [33,34]. The decrease in F F is however more severe for a-Si:H cell than for pm-Si:H cell.…”

Photostability of thermally-hydrosilylated silicon quantum dots

“…Two material properties are proposed to play critical roles in the SWE observed in a-Si:H lms: (1) disorder in the silicon network and (2) the presence of hydrogen. 29 These are also characteristics of the SiNC surface; thus, the elevated D center signal is postulated to be derived from unpaired electrons at the NC surface. At 4.2 nm, almost 50% of the silicon atoms in a SiNC lie on its surface.…”

Large-Scale Simulations ofa-Si:H: The Origin of Midgap States Revisited

“…This is still considered one of the major disadvantages of a-Si:H as a photovoltaic material, leading to a decrease in the light conversion efficiency by up to 30% [7]. From its early observation to date, experimental studies have provided evidence that photodegradation is accompanied by an increase in the density of states (DOS) in the energy gap of a-Si:H and associate it to the presence of microscopic structural defects (see, e.g., [2][3][4]9]). There is no doubt that dangling bonds (DBs) generate levels in the gap, but indications exist that other metastable and likely less localized defects must also contribute to the SWE [4,10,11].…”