N-type PbS colloidal-quantum-dot (CQD) films are fabricated using a controlled halide chemical treatment, applied in an inert processing ambient environment. The new materials exhibit a mobility of 0.1 cm(2) V(-1) s(-1) . The halogen ions serve both as a passivating agent and n-dope the films via substitution at surface chalcogen sites. The majority electron concentration across the range 10(16) to 10(18) cm(-3) is varied systematically.
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http://dx.doi.org/10.1002/adma.201202825 | DOI Listing |
Adv Mater
November 2022
Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
Solution-processed photodetectors based on colloidal quantum dots (CQDs) are promising candidates for short-wavelength infrared light sensing applications. Present-day CQD photodetectors employ a CQD active layer sandwiched between carrier-transport layers in which the electron-transport layer (ETL) is composed of metal oxides. Herein, a new class of ETLs is developed using n-type CQDs, finding that these benefit from quantum-size effect tuning of the band energies, as well as from surface ligand engineering.
View Article and Find Full Text PDFAdv Sci (Weinh)
August 2020
Colloidal quantum dots (CQDs) are of interest for optoelectronic applications owing to their tunable properties and ease of processing. Large-diameter CQDs offer optical response in the infrared (IR), beyond the bandgap of c-Si and perovskites. The absorption coefficient of IR CQDs (≈10 cm) entails the need for micrometer-thick films to maximize the absorption of IR light.
View Article and Find Full Text PDFACS Appl Mater Interfaces
April 2020
School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, China.
Silicon and PbS colloidal quantum dot heterojunction photodetectors combine the advantages of the Si device and PbS CQDs, presenting a promising strategy for infrared light detecting. However, the construction of a high-quality CQDs:Si heterojunction remains a challenge. In this work, we introduce an inverted structure photodetector based on n-type Si and p-type PbS CQDs.
View Article and Find Full Text PDFNat Commun
January 2020
Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON, M5S 3G4, Canada.
Control over carrier type and doping levels in semiconductor materials is key for optoelectronic applications. In colloidal quantum dots (CQDs), these properties can be tuned by surface chemistry modification, but this has so far been accomplished at the expense of reduced surface passivation and compromised colloidal solubility; this has precluded the realization of advanced architectures such as CQD bulk homojunction solids. Here we introduce a cascade surface modification scheme that overcomes these limitations.
View Article and Find Full Text PDFNat Commun
October 2018
Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon, 34103, Korea.
We introduce indium arsenide colloidal quantum dot films for photovoltaic devices, fabricated by two-step surface modification. Native ligands and unwanted oxides on the surface are peeled off followed by passivating with incoming atomic or short ligands. The near-infrared-absorbing n-type indium arsenide colloidal quantum dot films can be tuned in energy-level positions up to 0.
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