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

• Published in: Advanced science Vol. 5; no. 8; pp. 1800656 - n/a
• Main Authors: Tong, Xin, Kong, Xiang‐Tian, Wang, Chao, Zhou, Yufeng, Navarro‐Pardo, Fabiola, Barba, David, Ma, Dongling, Sun, Shuhui, Govorov, Alexander O., Zhao, Haiguang, Wang, Zhiming M., Rosei, Federico
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.08.2018; John Wiley and Sons Inc
• Subjects: Efficiency; Funding; Investigations; Lifetime; near‐infrared emission; Optical properties; photoelectrochemical cells; pyramidal structures; Quantum dots; Science; Sun; Canada; China; photoelectrochemical cells; quantum dots; pyramidal structures; near‐infrared emission
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.201800656

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. Colloidal heterostructured pyramidal “giant” core/shell quantum dots are developed and optical properties show near‐infrared photoluminescence (PL) emission (≈830 nm) and very long PL lifetime (in the microsecond range). The PL lifetime and simulation demonstrate their quasi‐type II band alignment and corresponding quantum dots‐sensitized photoanode exhibits a saturated photocurrent density as high as ≈5.5 mA cm−2 with good stability.