Optoelectronic Properties in Near‐Infrared Colloidal Heterostructured Pyramidal “Giant” Core/Shell Quantum Dots

Abstract

Colloidal heterostructured quantum dots (QDs) are promising candidates for next‐generation optoelectronic devices. In particular, “giant” core/shell QDs (g‐QDs) can be engineered to exhibit outstanding optical properties and high chemical/photostability for the fabrication of high‐performance optoelectronic devices. Here, the synthesis of heterostructured CuInSexS2− x (CISeS)/CdSeS/CdS g‐QDs with pyramidal shape by using a facile two‐step method is reported. The CdSeS/CdS shell is demonstrated to have a pure zinc blend phase other than typical wurtzite phase. The as‐obtained heterostructured g‐QDs exhibit near‐infrared photoluminescence (PL) emission (≈830 nm) and very long PL lifetime (in the microsecond range). The pyramidal g‐QDs exhibit a quasi‐type II band structure with spatial separation of electron–hole wave function, suggesting an efficient exciton extraction and transport, which is consistent with theoretical calculations. These heterostructured g‐QDs are used as light harvesters to fabricate a photoelectrochemical cell, exhibiting a saturated photocurrent density as high as ≈5.5 mA cm−2 and good stability under 1 sun illumination (AM 1.5 G, 100 mW cm−2). These results are an important step toward using heterostructured pyramidal g‐QDs for prospective applications in solar technologies.

Engineering the Optoelectronic Properties of Colloidal Alloyed Copper Chalcogenide Quantum Dots for High‐Efficiency Solar Energy Conversion

“…We attributed this emerging NIR PL emission, ultralong PL lifetime, and low PLQY to the formation of type‐II band structure in such core/shell QDs for radiative recombination of electrons in CdS shell with holes in CuSeS core,[7a,18] shown in Figure e. In addition, this ultralong lifetime is also related to the effective surface passivation and the pyramidal‐shaped structure in these core/shell QDs, as demonstrated in the literature …”

“…It is noted that the size of CuSeS core QDs in core/shell QDs reduced as compared with the size of core QDs before shell coating (≈4.3 ± 0.4 nm). This indicates the phenomenon of core shrinking during the growth of CdS shell, which is a typical process in the preparation of core/shell QDs …”

Reappraising the Luminescence Lifetime Distributions in Silicon Nanocrystals

“…Colloidal nanoparticles can be used in a manifold of applications including catalysis, medical treatments, and optoelectronic applications [ 1 – 4 ]. Semiconductor nanoparticles are of particular interest for light emission, photovoltaic, and photocatalytic applications [ 5 , 6 ]. Silicon nanocrystals (SiNCs) are a focus of current attention owing to the tunable emission properties [ 7 ] as well as the abundance and biocompatibility of silicon [ 8 ].…”

Smart Sensing Systems Using Wearable Optoelectronics

“…To this end, quite a few research groups are attempting to develop environment‐friendly QDs using nontoxic materials such as carbon QDs, silicon QDs, and ternary compound QDs. Nonetheless, compared with existing QDs based on heavy metals, nontoxic QDs have a lower emission efficiency and thermal/chemical stability, which warrant ongoing studies to overcome such limitations . Meanwhile, optoelectronics wearable sensors based on hybrid organic–inorganic metal halide perovskites such as CH 3 NH 3 PbX 3 (X = Cl, Br, I) have been well documented.…”