Hole Transfer Dynamics of 2D CdSeS Alloy Nanoplatelets for Photon-to-Current Conversion

Abstract

Colloidal two-dimensional (2D) CdSe nanoplatelets (NPLs) with strong quantum confinement in the vertical direction are being explored extensively, because of their potential optoelectronic and photonic applications. Here, we have synthesized CdSeS alloy NPLs by incorporating S atoms in the CdSe NPLs to tune their optical properties and investigated the charge transfer dynamics of alloy NPLs by preparing a hybrid with a 4-amino thiophenol (ATP) molecule. Hole transfer from alloy NPLs to the ATP molecule is evident from femtosecond transient absorption (TA) spectroscopy study in a time scale of 3.1 ps. Efficient charge separation from alloy NPLs to ATP molecules is beneficial for photon-to-current conversion and optoelectronic applications. Photodetector devices based on hybrid alloy NPLs exhibit high photocurrent, fast response (∼114 ms), and high detectivity of 2.5 × 10 10 Jones.

Introducing Ag Dopants into CdSe Nanoplatelets (NPLs) Leads to Effective Charge Separation for Better Photodetector Performance

“…where $${{J}_{Ph}}$$ ,$${\ {P}_{light}}$$ ,$${\ {I}_{Ph}}$$ , and $${A}$$ denote the photocurrent density in μA/cm 2 , input light intensity in mW/cm 2 , photocurrent in μA, and active area of the device in cm 2 respectively [9b] . The maximum responsivity of Ag: CdSe‐based PDs is 2.4 mA/W which is higher than CdSe‐based PDs (1.5 mA/W) proving more responsive than the latter (Figure 5e).…”

“…where $${q}$$ and $${{J}_{d}}$$ are the electronic charges in coulomb and dark current in μA/cm 2, respectively [9b] . The detectivity increases with decreasing input light intensity.…”