Short-Wave Infrared Optoelectronics with Colloidal CdHgSe/ZnCdS Core/Shell Nanoplatelets

Abstract

Colloidal semiconductor nanocrystals (NCs) are an efficient and cost-effective class of nanomaterials for optoelectronic applications. Advancements in NC-based optoelectronic devices have resulted from progress in synthetic chemistry, adjustable surface properties, and optimized device architectures. Semiconductor nanoplatelets (NPLs) stand out among other NCs due to their precise growth control, yielding uniform thickness with submonolayer roughness. In this study, we demonstrate the versatility of core/shell Cd _x Hg_1-x Se/Zn _y Cd_1-y S NPLs for optoelectronic applications in the short-wave infrared (SWIR) spectral range. We employed the very same core/shell NPLs for the fabrication of light-emitting diodes and photodetectors alike, achieving significant performance in both electroluminescence (external quantum efficiency ranging from 7.5% at 1280 nm to 3.8% at 1550 nm) and detection (responsivity of 0.24 A W^-1 at 1200 nm).

Figure 1

(a) Normalized optical absorption and (b) PL spectra of the three Cd_xHg_1–xSe/Zn_yCd_1–yS core/shell NPL samples (O, E, and C) in TCE dispersions. TEM images of (c) O, (d) E, and (e) C NPLs.

Figure 2

(a) Schematic of the LED architecture. (b) Flat energy band diagram of the LED. (c) SEM cross-sectional image of a typical LED. (d) J-V-R curves of the three types of LEDs. (e) EQE versus current density curves. (f) EL spectra of LEDs with different active layers.

Figure 3

(a) Schematic, (b) cross-section SEM image, and (c) flat band diagram of a Cd_xHg_1–xSe/Zn_yCd_1–yS NPL photodiode. (d) FTIR spectra of a Cd_xHg_1–xSe/Zn_yCd_1–yS NPL film before and after ligand exchange with EDT.

Figure 4

(a) Response spectrum, (b) J–V curves, (c) open circuit voltage response to 1200 nm light, and (d) reproducibility of the response to 1200 nm light pulses of the fabricated photodiode.