Nonthermal plasma techniques were used to synthesize phorphorus and boron co-doped Si nanocrystals (PB:Si NCs) with diameters (DNC) ranging from 2.9–7.3 nm. Peak photoluminescence (PL) emission energies for all PB:Si NC diameters are ca. 400–500 meV lower than the excitonic emission values in intrinsic Si NCs, which can be attributed to prevalent donor-acceptor (D-A) transitions within the co-doped system. This D–A transition model is further evidenced by PL lifetimes within the range of 40–80 ms, faster than what is observed for intrinsic Si NCs. By reducing the level of confinement within PB:Si NCs (i.e., DNC &gt; 4 nm), the near-infrared (NIR)-emitting D–A transitions were observed to red-shift below the bandgap of bulk Si (1.12 eV). The PL quantum yield (PLQY) was quantified for a range of DNC and shows that the plasma method can achieve reasonably high PLQY values (12% for DNC = 2.9 nm), even without any optimization of the synthesis or surface chemistry. We posit that perfect charge compensation cannot explain these results and propose a model in which dominant n-type doping accounts for the observations. Ultimately, these results demonstrate that nonthermal plasma synthesis is a viable pathway for preparing PB:Si NCs featuring NIR sub-band gap D–A transitions with relatively high quantum yields.

Nonthermal plasma-synthesized PB co-doped Si NCs: New approach to non-toxic NIR-emitters

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.