Evidence of Energy and Hole Transfer between 2D CdSe0.7Te0.3 Alloy NPLs with Porphyrin Molecules.

Abstract

Colloidal two-dimensional (2D) nanoplatelets (NPLs) have been extensively studied owing to promising potential in optoelectronic applications. Here, we have reported the preparation of 2D CdSeTe alloy NPLs and investigated their energy and charge transfer with porphyrin molecules. The red shifting in the optical properties suggests the change in the band gaps. Furthermore, the energy and the charge transfer are evident in the composite of CdSeTe alloy NPLs with 5,10,15,20-tetra(4pyridyl)-porphyrin (TpyP) molecules. The quenching in the photoluminescence (PL) spectra and PL decay time supports the energy transfer (~61 % efficiency) and the charge transfer. The thermodynamically feasible hole transfer is evidenced by the band alignment of the alloy NPLs and TpyP molecules, which is further supported by a transient absorption spectroscopy (TAS) study. The TA study found the hole transfer within ~3 ps time scale, proving the effective charge carrier separation for better optoelectronic applications.