Colloidal Optoelectronics

Hilmi Volkan Demir^b

^aBilkent University UNAM, Department of Electrical and Electronics Engineering, Department of Physics, 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 Emerging Light Emitting Materials 2025 (EMLEM25)

La Canea, Greece, 2025 October 8th - 10th

Organizers: Maksym Kovalenko and Grigorios Itskos

Invited Speaker, Hilmi Volkan Demir, presentation 003
Publication date: 17th July 2025

Semiconductor nanocrystals, offering a market volume exceeding 5 billion Euros annually, have attracted great interest in quality lighting and displays. Such colloidal semiconductors enable enriched color conversion essential to superior lighting and displays. These colloids span different types and heterostructures of semiconductors from colloidal quantum dots to wells. In this talk, we will focus on atomically flat, tightly confined, quasi-2-dimensional wells, also popularly nick-named ‘nanoplatelets’, particularly for use in lighting and displays [1-14]. Also, we will present a powerful, large-area, orientation-controlled self-assembly technique for orienting these quantum wells either all face down or all edge up and demonstrate three-dimensional constructs of their oriented self-assemblies with monolayer precision [8,9]. Among their extraordinary features important to applications in lighting and displays, we will show record high efficiency from their colloidal LEDs [10,11] and record high gain coefficients and record low lasing thresholds from their colloidal laser media [1,12,13] using their heterostructures [2-6,10] and/or oriented assemblies [8,9,11]. We will finally discuss the use of colloidal quantum wells intimately integrated into metasurfaces to make a new class of colloidal meta-devices [14]. Given their current accelerating progress, these solution-processed nanocrystals hold great promise to challenge their epitaxial thin-film counterparts in semiconductor optoelectronics.

References:

[1] [1] Guzelturk B.; Pelton M;, Olutas M.; Demir H. V. Giant Modal Gain Coefficients in Colloidal II−VI Nanoplatelets. Nano Letters 19, 277 (2019)

[2] [2] Altıntas Y.; Gungor K.;, Gao Y.; Sak M.; Quliyeva U.;, Bappi G.;,Mutlugun 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

[3] [3] Taghipour, N., Delikanli, S., Shendre, S.; Demir H.V. et al. Sub-single exciton optical gain threshold in colloidal semiconductor quantum wells with gradient alloy shelling. Nat Commun 11, 3305 (2020).

[4] [4] Shabani F.; Dehghanpour Baruj H.; Yurdakul I.; Delikanli S.; Gheshlaghi N.; Isik F.; Liu B.; Altintas Y.; Canımkurbey B.; Demir H. V. Deep-Red-Emitting Colloidal Quantum Well Light-Emitting Diodes Enabled through a Complex Design of Core/Crown/ Double Shell Heterostructure Small 18, 2106115 (2022)

[5] [5] Liang X.; Durmusoglu E. G.; Lunina M.; Hernandez-Martinez P. L..; Valuckas V.; Yan F.; Lekina Y.; Sharma V. K.; Yin T.; Ha S. T.; Shen Z. X.; Sun H.; Kuznetsov A.; Demir H. V. Near-Unity Emitting Widely Tailorable,and Stable Exciton Concentrators Built from Doubly Gradient 2D Semiconductor Nanoplatelets. ACS Nano 17, 19981 (2023)

[6] [6] S. Delikanli et al., On the Rational Design of Core/(multi)-crown Type-II Hetero-nanoplatelets. JACS 145, 12033 (2023)

[7] [7] Y. Junhong, et al., Optical signatures of lattice strain in chemically doped colloidal quantum wells. Nature Communications 16, 823 (2025)

[8] [8] O. Erdem et al., Orientation-Controlled Nonradiative Energy Transfer to Colloidal Nanoplatelets: Engineering Dipole Orientation Factor. Nano Letters 19, 4297 (2019)

[9] [9] O. Erdem et al., Thickness-Tunable Self-Assembled Colloidal Nanoplatelet Films Enable Ultra-Thin Optical Gain Media. Nano Letters 20, 6459 (2020)

[10] [10] B. Liu et al., Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth. Advanced Materials 32, 1905824 (2020)

[11] [11] H. D. Baruj et al., Highly-Directional, Highly-Efficient Solution-Processed Light-Emitting Diodes of All-Face-Down Oriented Colloidal Quantum Well Self-Assembly. Small 19, 2206582 (2023)

[12] [12] J. Maskoun et al., Optical Microfluidic Waveguides and Solution Lasers of Colloidal Semiconductor Quantum Wells. Advanced Materials 33, 2007131 (2021)

[13] [13] F. Isik et al., “Giant” Colloidal Quantum Well Heterostructures of CdSe@CdS Core@Shell Nanoplatelets from 9.5 to 17.5 Monolayers in Thickness Enabling Ultra-High Gain Lasing. Small 20, 2309494 (2024)

[14] [14] S. T. Ha et al., Optoelectronic Metadevices. Science 386, eadm7442 (2024)

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