Trap-State-Induced Becquerel Type of Photoluminescence Decay in DPA-Activated Silicon Nanocrystals

A suitable description of the photoluminescence dynamics in a complex system such as an ensemble of semiconductor nanocrystals can bring invaluable insight into its carrier dynamics. In this contribution, we study a system of silicon nanocrystals sensitized by light-harvesting diphenylanthracene molecules enhancing their absorption. The emission-wavelength-resolved photoluminescence decay of this system can be well-described by the Becquerel (compressed hyperbola) function, featuring a characteristic power-law-like tail. This shape of the photoluminescence decay function is linked to a model based on trapping and releasing of excited carriers, which are the cause of the longer tail. Our model allows us to estimate the value of the trap capture cross-section of σt ≈ 1.5 × 10-16 cm2.