Copper-Doped Colloidal Quantum Wells: synthesis, solar light harvesting, lasing, and mutual energy transfer
Manoj Sharma a b, Ashma Sharma a b, Kivanc Gungor b, Junhong Yu a, Mingjie Li c, Tze-Chien Sum c, Cuong Dang a, Hilmi Volkan Demir a b c
a LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
b Department of Electrical and Electronics Engineering, Department of Physics, and UNAM–Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey.
c School of Physical and Mathematical Sciences, Nanyang Technological University, 639798, Singapore
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#NCFun19. Fundamental Processes in Semiconductor Nanocrystals
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Ivan Infante and Jonathan Owen
Poster, Manoj Sharma, 343
Publication date: 16th July 2019

In the past two decades doped nanocrystals (NCs) have attracted a lot of attention because of their interesting electronic structure and unique optical properties. Recently, copper (Cu) - doped NCs have been studied extensively for understanding of their broadband Stokes-shifted emission and to utilize them in different optoelectronic applications including luminescent solar concentrators (LSCs). Here we show successful Cu-doping in atomically flat NCs, the colloidal quantum wells (CQWs), resulting strong broadband, largely Stokes-shifted and tunable visible-near-infrared (NIR) emission. [1-2] We have divided this work into four complementary parts. (i) Synthesis and understanding of the detailed photophysics of Cu-doped CdSe CQWs possessing excellent optical properties, which include very high PL quantum efficiency with step-like absorption profiles. (ii) Based on these exceptional properties, these NIR emitting doped CQWs were successfully applied to LSCs and have shown superior performance for solar light harvesting. Using detailed reabsorption studies, we demonstrated our doped CQWs as excellent candidates for next generation LSCs.[1,3] (iii) By utilizing the interaction between the quantum confined host carriers (band edge) and the Cu dopant ions, we observed room-temperature radiative biexciton states in these doped CQWs under continuous-wave excitation at pumping fluence as low as ~10 W/cm2. Using the optical gain arising from the biexciton population, doped CQWs film embedded in the vertical cavity surface-emitting laser (VCSEL) structure yields an ultralow lasing threshold under sub-nanosecond pulsed excitation. These findings set our doped-CdSe CQWs as a new member for correlated excitonic studies and biexciton lasing devices. (iv) By utilizing dopant emission from Cu- doped CQWs, we propose a mutual fluorescence resonance energy transfer (FRET) between two distinct CQWs which play the role of donor and acceptor simultaneously. Using detailed time-resolved and photoluminescence excitation spectroscopies we demonstrated that band-edge excitons in Cu-doped CQWs effectively transfer the excitation to excitons in undoped CQWs whose energy is also harvested backwards by the dopants. This unique mutual FRET mechanism allows controllable conversion among three primary colors in the CQW complex. [4] Overall, these efforts allowed to utilize doping concepts in 2D atomically flat CQWs to their full potential, which can be extended into different host cores/dopants and new 2D architectures for future color conversion applications.

References

[1] Sharma, M.; Gungor, K.; Yeltik, A.; Olutas, M.; Guzelturk, B.; Kelestemur, Y.; Erdem, T.; Delikanli, S.; McBride, J. R.; Demir, H. V. Near-Unity Emitting Copper-Doped Colloidal Semiconductor Quantum Wells for Luminescent Solar Concentrators. Adv. Mater. 2017, 29, 1700821

 [2]. Sharma, M.; Olutas, M.; Yeltik, A.; Kelestemur, Y.; Sharma, A.; Delikanli, S.; Guzelturk, B.; Gungor, K.; McBride, J. R.; Demir, H. V. Understanding the Journey of Dopant Copper Ions in Atomically Flat Colloidal Nanocrystals of CdSe Nanoplatelets Using Partial Cation Exchange Reactions. Chem. Mater. 2018, 30, 3265– 3275

[3] Sharma, A; Sharma, M; Gungor, K; Olutas, M; Dede, D; Demir, H.V. Near-Infrared-Emitting Five Monolayer Thick Copper Doped CdSe Nanoplatelets, Adv. Optical Mater, 2019, 1900831 DOI:10.1002/adom.201900831

[4] Yu, J; Sharma, M; Delikanli, S; Birowosuto, M.D; Demir, H.V; Dang, C, Mutual Energy Transfer in a Binary Colloidal Quantum Well Complex, J. Phys. Chem. Lett., 10, 5193-5199 (2019).

Singapore National Research Foundation under the programs of NRF-NRFI2016-08

Singapore Ministry of Education through AcRF Tier1 grant (MOE2017-T1-002-142)

The Competitive Research Program NRF-CRP14-2014-03

Singapore Ministry of Education AcRF Tier-1 grant (MOE-RG178/17)

ESF-EURYI

TUBA-GEBIP

© Fundació Scito
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