Emerging Optoelectronics of Colloidal Quantum Wells: Pushing the Limits

Hilmi Volkan Demir^b

^aBilkent University Department of Electrical and Electronics Engineering, Department of Physics, UNAM--Institute of Materials Science and Nanotechnology, Ankara, Turkey

^bNTU Singapore – Nanyang Technological University School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Singapore

Proceedings of Internet NanoGe Conference on Nanocrystals (iNCNC)

Online, Spain, 2021 June 28th - July 2nd

Organizers: Maksym Kovalenko, Maria Ibáñez, Peter Reiss and Quinten Akkerman

Invited Speaker, Hilmi Volkan Demir, presentation 026
DOI: https://doi.org/10.29363/nanoge.incnc.2021.026
Publication date: 8th June 2021

Semiconductor nanocrystals have attracted great interest for color conversion and enrichment in quality lighting and displays. Optical properties of these solution‑processed nanostructures are conveniently controlled by tailoring their size, shape and composition in an effort to realize high‑performance light generation and lasing. These colloids span different types and heterostructures of semiconductors in the forms of quantum dots and rods to the latest sub‑family of nanocrystals, the colloidal quantum wells (CQWs). In this talk, we will introduce the emerging field of semiconductor nanocrystal optoelectronics with most recent examples of their photonic structures and optoelectronic devices employing such atomically‑flat, tightly‑confined, quasi‑2‑dimensional CQWs, also popularly nick‑named ‘nanoplatelets’. Among various extraordinary features of theirs, we will show that these CQWs enable record high optical gain coefficients [1] and can achieve gain thresholds at the level of sub‑single exciton population per CQW on the average [2], empowered by carefully engineering their heterostructure [3]. Next, we will present a new, powerful, large-area self‑assembly tool for orientation‑controlling of these nanoplatelets [4], which provides us with the ability to tune and master their excitonic properties in their ensemble as well as the level of achievable energy transfer among them and with other nearby species. Using three‑dimensional constructs of face‑down self‑assembled slabs of CQWs with monolayer precision, we will demonstrate ultrathin optical gain media and lasers of these oriented CQW assemblies [5]. Finally, we will show record high‑efficiency colloidal LEDs using CQWs employed as the electrically‑driven active emitter layer [6] and record low-threshold solution lasers using the same CQWs employed as the optically‑pumped fluidic gain medium [7]. Given their current accelerating progress, these solution‑processed quantum well materials hold great promise to challenge their epitaxial thin‑film counterparts in semiconductor optoelectronics in the near future.

References:

[1] [1] Guzelturk, B.; Pelton M.; Demir H.V. Giant Modal Gain Coefficients in Colloidal II–VI Nanoplatelets. Nano Lett. 2019, 19,1, 277-282.

[2] [2] Taghipour, N.; Delikanli, S.; Shendre, S..; et al. Sub-single exciton optical gain threshold in colloidal semiconductor quantum wells with gradient alloy shelling. Nat Commun. 2020, 11, 3305.

[3] [3] Altintas Y.; Gungor K.; Gao Y.; Sak M.; Quliyeva U.; Bappi G.; Mutlugün E.; Sargent E. H.; Demir H.V. Giant Alloyed Hot Injection Shells Enable Ultralow Optical Gain Threshold in Colloidal Quantum Wells .ACS Nano, 2019, 13, 9, 10662–10670.

[4] [4] Erdem O.; Gungor K.; Guzelturk B.; Tanriover I.; Sak M.; Olutas M.; Dede D.; Kelestemur Y.; Demir H.V. Orientation-Controlled Nonradiative Energy Transfer to Colloidal Nanoplatelets: Engineering Dipole Orientation Factor.Nano Lett. 2019, 19, 7, 4297–4305.

[5] [5] Erdem O.; Foroutan S.; Gheshlaghi N.; Guzelturk B.; Altintas Y.; Demir H.V, Thickness-Tunable Self-Assembled Colloidal Nanoplatelet Films Enable Ultrathin Optical Gain Media. Nano Lett. 2020, 20, 9, 6459–6465.

[6] [6] Baiquan L.; Altintas Y.; Wang L.; Shendre S.; Sharma M.; Sun H.; Mutlugun E.; Demir H.V. Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth. Adv. Mater. 2020, 32, 19055824.

[7] Maskoun J.; Gheslaghi N.; Isik F.; Delikanli S.; Erdem O.; Erdem E.Y.; Demir H.V. Optical Microfluidic Waveguides and Solution Lasers of Colloidal Semiconductor Quantum Wells. Adv. Mater. 2021, 33, 2007131.

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