Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals

N. X. Ca, N. T. Hien, P. M. Tan, T. L. Phan, L. D. Thanh, P. V. Do, N. Q. Bau, V. T.K. Lien, H. T. Van

Research output: Contribution to journalArticleResearchpeer-review

Abstract

We have used wet chemical methods to fabricate colloidal CdSe/CdSm/ZnSen core/intermediate/shell (C/I/S) nanocrystals (NCs), where m = 1 and 2 and n = 1–4 are the number of monolayers. The growth was monitored by using Raman and UV–vis spectroscopy, which demonstrated the formation of correct CdSe/CdSm/ZnSen C/I/S NCs. X-ray diffraction studies proved single-phase NCs crystallized in the zincblende-type structure. Photoluminescence (PL) studies have indicated that after photoexcitation C/I/S NCs generate simultaneously type-I and type-II emissions, namely E I and E II , associated with CdSe/CdSm and CdSm/ZnSen structures, respectively. For a specific value of m = 2, we have found the redshift of both E I and E II emissions when n is increased from 1 to 4. The PL studies versus the laser-excitation power (P ex ) up to about four orders of magnitude allow us to identify the origin of two emissions. A large blueshift of the E II peak is ascribed to the band bending effect resulting from the spatially separated photoexcited carriers in type-II NCs. It appears that the dependence of the E II peak on the cube root of P ex (P ex 1/3 ) is linear while that of the E I peak on P ex 1/3 is almost constant. In this work, we also point out that the emission intensity (I) of E I and E II can be tuned by changing the values of n and P ex , where I obeys a power law I∝P ex k , with k = 0.7–1.0 dependent on the emission type. The nature of these phenomena is discussed in comparison with previous studies on C/S and C/I/S nanoheterostructures.

Original languageEnglish
Pages (from-to)144-151
Number of pages8
JournalJournal of Alloys and Compounds
Volume791
DOIs
Publication statusPublished - 30 Jun 2019

Fingerprint

Nanocrystals
Photoluminescence
Laser excitation
Photoexcitation
Monolayers
Spectroscopy
X ray diffraction

Cite this

Ca, N. X., Hien, N. T., Tan, P. M., Phan, T. L., Thanh, L. D., Do, P. V., ... Van, H. T. (2019). Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals. Journal of Alloys and Compounds, 791, 144-151. https://doi.org/10.1016/j.jallcom.2019.03.333
Ca, N. X. ; Hien, N. T. ; Tan, P. M. ; Phan, T. L. ; Thanh, L. D. ; Do, P. V. ; Bau, N. Q. ; Lien, V. T.K. ; Van, H. T. / Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals. In: Journal of Alloys and Compounds. 2019 ; Vol. 791. pp. 144-151.
@article{4865daab289d4f5597f359b7ef5e7409,
title = "Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals",
abstract = "We have used wet chemical methods to fabricate colloidal CdSe/CdSm/ZnSen core/intermediate/shell (C/I/S) nanocrystals (NCs), where m = 1 and 2 and n = 1–4 are the number of monolayers. The growth was monitored by using Raman and UV–vis spectroscopy, which demonstrated the formation of correct CdSe/CdSm/ZnSen C/I/S NCs. X-ray diffraction studies proved single-phase NCs crystallized in the zincblende-type structure. Photoluminescence (PL) studies have indicated that after photoexcitation C/I/S NCs generate simultaneously type-I and type-II emissions, namely E I and E II , associated with CdSe/CdSm and CdSm/ZnSen structures, respectively. For a specific value of m = 2, we have found the redshift of both E I and E II emissions when n is increased from 1 to 4. The PL studies versus the laser-excitation power (P ex ) up to about four orders of magnitude allow us to identify the origin of two emissions. A large blueshift of the E II peak is ascribed to the band bending effect resulting from the spatially separated photoexcited carriers in type-II NCs. It appears that the dependence of the E II peak on the cube root of P ex (P ex 1/3 ) is linear while that of the E I peak on P ex 1/3 is almost constant. In this work, we also point out that the emission intensity (I) of E I and E II can be tuned by changing the values of n and P ex , where I obeys a power law I∝P ex k , with k = 0.7–1.0 dependent on the emission type. The nature of these phenomena is discussed in comparison with previous studies on C/S and C/I/S nanoheterostructures.",
keywords = "CdSe/CdS/ZnSe nanocrystals, Spectrometric studies, Type-I/type-II heterostructures",
author = "Ca, {N. X.} and Hien, {N. T.} and Tan, {P. M.} and Phan, {T. L.} and Thanh, {L. D.} and Do, {P. V.} and Bau, {N. Q.} and Lien, {V. T.K.} and Van, {H. T.}",
year = "2019",
month = "6",
day = "30",
doi = "10.1016/j.jallcom.2019.03.333",
language = "English",
volume = "791",
pages = "144--151",
journal = "Journal of Alloys and Compounds",
issn = "0925-8388",
publisher = "Elsevier",

}

Ca, NX, Hien, NT, Tan, PM, Phan, TL, Thanh, LD, Do, PV, Bau, NQ, Lien, VTK & Van, HT 2019, 'Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals', Journal of Alloys and Compounds, vol. 791, pp. 144-151. https://doi.org/10.1016/j.jallcom.2019.03.333

Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals. / Ca, N. X.; Hien, N. T.; Tan, P. M.; Phan, T. L.; Thanh, L. D.; Do, P. V.; Bau, N. Q.; Lien, V. T.K.; Van, H. T.

In: Journal of Alloys and Compounds, Vol. 791, 30.06.2019, p. 144-151.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Tunable dual emission in type-I/type-II CdSe/CdS/ZnSe nanocrystals

AU - Ca, N. X.

AU - Hien, N. T.

AU - Tan, P. M.

AU - Phan, T. L.

AU - Thanh, L. D.

AU - Do, P. V.

AU - Bau, N. Q.

AU - Lien, V. T.K.

AU - Van, H. T.

PY - 2019/6/30

Y1 - 2019/6/30

N2 - We have used wet chemical methods to fabricate colloidal CdSe/CdSm/ZnSen core/intermediate/shell (C/I/S) nanocrystals (NCs), where m = 1 and 2 and n = 1–4 are the number of monolayers. The growth was monitored by using Raman and UV–vis spectroscopy, which demonstrated the formation of correct CdSe/CdSm/ZnSen C/I/S NCs. X-ray diffraction studies proved single-phase NCs crystallized in the zincblende-type structure. Photoluminescence (PL) studies have indicated that after photoexcitation C/I/S NCs generate simultaneously type-I and type-II emissions, namely E I and E II , associated with CdSe/CdSm and CdSm/ZnSen structures, respectively. For a specific value of m = 2, we have found the redshift of both E I and E II emissions when n is increased from 1 to 4. The PL studies versus the laser-excitation power (P ex ) up to about four orders of magnitude allow us to identify the origin of two emissions. A large blueshift of the E II peak is ascribed to the band bending effect resulting from the spatially separated photoexcited carriers in type-II NCs. It appears that the dependence of the E II peak on the cube root of P ex (P ex 1/3 ) is linear while that of the E I peak on P ex 1/3 is almost constant. In this work, we also point out that the emission intensity (I) of E I and E II can be tuned by changing the values of n and P ex , where I obeys a power law I∝P ex k , with k = 0.7–1.0 dependent on the emission type. The nature of these phenomena is discussed in comparison with previous studies on C/S and C/I/S nanoheterostructures.

AB - We have used wet chemical methods to fabricate colloidal CdSe/CdSm/ZnSen core/intermediate/shell (C/I/S) nanocrystals (NCs), where m = 1 and 2 and n = 1–4 are the number of monolayers. The growth was monitored by using Raman and UV–vis spectroscopy, which demonstrated the formation of correct CdSe/CdSm/ZnSen C/I/S NCs. X-ray diffraction studies proved single-phase NCs crystallized in the zincblende-type structure. Photoluminescence (PL) studies have indicated that after photoexcitation C/I/S NCs generate simultaneously type-I and type-II emissions, namely E I and E II , associated with CdSe/CdSm and CdSm/ZnSen structures, respectively. For a specific value of m = 2, we have found the redshift of both E I and E II emissions when n is increased from 1 to 4. The PL studies versus the laser-excitation power (P ex ) up to about four orders of magnitude allow us to identify the origin of two emissions. A large blueshift of the E II peak is ascribed to the band bending effect resulting from the spatially separated photoexcited carriers in type-II NCs. It appears that the dependence of the E II peak on the cube root of P ex (P ex 1/3 ) is linear while that of the E I peak on P ex 1/3 is almost constant. In this work, we also point out that the emission intensity (I) of E I and E II can be tuned by changing the values of n and P ex , where I obeys a power law I∝P ex k , with k = 0.7–1.0 dependent on the emission type. The nature of these phenomena is discussed in comparison with previous studies on C/S and C/I/S nanoheterostructures.

KW - CdSe/CdS/ZnSe nanocrystals

KW - Spectrometric studies

KW - Type-I/type-II heterostructures

UR - http://www.scopus.com/inward/record.url?scp=85063338678&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2019.03.333

DO - 10.1016/j.jallcom.2019.03.333

M3 - Article

VL - 791

SP - 144

EP - 151

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

SN - 0925-8388

ER -