I. , B. D. The-support-from-agence-nationale-de-la-recherche-through, H. Grant-nanodose, R. E. , S. I. Lhuillier et al., are also supported by the Region Ile-de-France in the framework of DIM Nano-K, from ANR within the Investissements d'Avenir programme ANR-11-IDEX-0004?02, and within the framework of the Cluster of Excellence MATISSE. We acknowledge the use of cleanroom facilities from the consortium " Salles Blanches Paris Centre ? SBPC, Nano Lett, vol.16, p.1282, 2016.

J. S. Joo, S. G. Son, J. H. Kwon, T. Yu, and . Hyeon, Low-Temperature Solution-Phase Synthesis of Quantum Well Structured CdSe Nanoribbons, Journal of the American Chemical Society, vol.128, issue.17, p.5632, 2006.
DOI : 10.1021/ja0601686

S. Lhuillier, S. Pedetti, B. Ithurria, H. Nadal, B. Heuclin et al., Two-Dimensional Colloidal Metal Chalcogenides Semiconductors: Synthesis, Spectroscopy, and Applications, Accounts of Chemical Research, vol.48, issue.1, p.22, 2015.
DOI : 10.1021/ar500326c

URL : https://hal.archives-ouvertes.fr/hal-01438557

B. Nasilowski, E. Mahler, S. Lhuillier, B. Ithurria, and . Dubertret, Two-Dimensional Colloidal Nanocrystals, Chemical Reviews, vol.116, issue.18, p.10934, 2016.
DOI : 10.1021/acs.chemrev.6b00164

URL : https://hal.archives-ouvertes.fr/hal-01419586

F. D. Riedinger, A. Ott, S. Mule, P. N. Mazzotti, S. J. Kn?-usel et al., An intrinsic growth instability in isotropic materials leads to quasi-two-dimensional nanoplatelets, Nature Materials, vol.113
DOI : 10.1103/PhysRevLett.113.156803

B. Chen, B. Nadal, H. Mahler, B. Aubin, and . Dubertret, Quasi-2D Colloidal Semiconductor Nanoplatelets for Narrow Electroluminescence, Advanced Functional Materials, vol.30, issue.3, p.295, 2014.
DOI : 10.1002/adfm.201301711

R. Benchamekh, N. A. Gippius, J. Even, M. O. Nestoklon, J. Jancu et al., Tight-binding calculations of image-charge effects in colloidal nanoscale platelets of CdSe, Physical Review B, vol.89, issue.3, p.35307, 2014.
DOI : 10.1103/PhysRevB.89.035307

URL : https://hal.archives-ouvertes.fr/hal-00942566

Q. Grim, S. Christodoulou, F. Di-stasio, R. Krahne, R. Cingolani et al., Continuous-wave biexciton lasing at room temperature using solution-processed quantum wells, Nature Nanotechnology, vol.134, issue.11, p.891, 2014.
DOI : 10.1038/nnano.2014.213

Y. Guzelturk, M. Kelestemur, S. Olutas, H. V. Delikanli, and . Demir, Amplified Spontaneous Emission and Lasing in Colloidal Nanoplatelets, ACS Nano, vol.8, issue.7, p.6599, 2014.
DOI : 10.1021/nn5022296

S. Ithurria and D. V. Talapin, Colloidal Atomic Layer Deposition (c-ALD) using Self-Limiting Reactions at Nanocrystal Surface Coupled to Phase Transfer between Polar and Nonpolar Media, Journal of the American Chemical Society, vol.134, issue.45, p.18585, 2012.
DOI : 10.1021/ja308088d

B. Mahler, B. Nadal, C. Bouet, G. Patriarche, and B. Dubertret, Core/Shell Colloidal Semiconductor Nanoplatelets, Journal of the American Chemical Society, vol.134, issue.45, p.18591, 2012.
DOI : 10.1021/ja307944d

A. Prudnikau, A. Chuvilin, and M. Artemyev, CdSe???CdS Nanoheteroplatelets with Efficient Photoexcitation of Central CdSe Region through Epitaxially Grown CdS Wings, Journal of the American Chemical Society, vol.135, issue.39, p.14476, 2013.
DOI : 10.1021/ja401737z

S. Pedetti, S. Ithurria, H. Heuclin, G. Patriarche, and B. Dubertret, Type-II CdSe/CdTe Core/Crown Semiconductor Nanoplatelets, Journal of the American Chemical Society, vol.136, issue.46, p.16430, 2014.
DOI : 10.1021/ja509307m

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J. Hermier et al., Towards non-blinking colloidal quantum??dots, Nature Materials, vol.85, issue.8, p.659, 2008.
DOI : 10.1038/nmat2222

P. Harrison, Quantum Wells, Wires and Dots, 2005.
DOI : 10.1002/9781118923337

URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.620.1795

O. Madelung, M. Schulz, and H. Weiss, Numerical Data and Functional Relationships in Science and Technology, New Series. Group III: Crystal and Solid State Physics, III/ 17. Intrinsic Properties of Group IV Elements and III?V, II?VI, and I?VII Compounds, 1982.

S. Z. Karazhanov and L. C. Voon, Ab initio Studies of the Band Parameters of III???V and II???VI Zinc-Blende Semiconductors, Semiconductors, vol.39, issue.2, p.161, 2005.
DOI : 10.1134/1.1864192

R. Dalven, Calculation of effective masses in cubic CdS and CdSe, Physica Status Solidi (b), vol.32, issue.1, p.23, 1971.
DOI : 10.1002/pssb.2220480150

L. Quiroga, F. J. Rodr-iguez, A. Camacho, and C. Tejedor, Electronic and optical properties of ZnSe-ZnS effective-mass strained superlattices, Physical Review B, vol.42, issue.17, p.11198, 1990.
DOI : 10.1103/PhysRevB.42.11198

-. Wei and A. Zunger, orbitals, Applied Physics Letters, vol.72, issue.16, p.2011, 1998.
DOI : 10.1016/0022-3697(83)90064-1

D. Sarma, P. K. Santra, S. Mukherjee, and A. Nag, X-ray Photoelectron Spectroscopy: A Unique Tool To Determine the Internal Heterostructure of Nanoparticles, Chemistry of Materials, vol.25, issue.8, p.1222, 2013.
DOI : 10.1021/cm303567d

L. Mahler, L. Guillemot, S. Bossard-giannesini, D. Ithurria, A. Pierucci et al., Metallic Functionalization of CdSe 2D Nanoplatelets and Its Impact on Electronic Transport, The Journal of Physical Chemistry C, vol.120, issue.23, p.12351, 2016.
DOI : 10.1021/acs.jpcc.6b02101

URL : https://hal.archives-ouvertes.fr/hal-01347065

E. B. Katari, V. L. Colvin, and A. P. , X-ray Photoelectron Spectroscopy of CdSe Nanocrystals with Applications to Studies of the Nanocrystal Surface, The Journal of Physical Chemistry, vol.98, issue.15, p.4109, 1994.
DOI : 10.1021/j100066a034

S. Lhuillier, A. Ithurria, T. Descamps-mandine, R. Douillard, X. Z. Castaing et al., Investigating the n- and p-Type Electrolytic Charging of Colloidal Nanoplatelets, The Journal of Physical Chemistry C, vol.119, issue.38, p.21795, 2015.
DOI : 10.1021/acs.jpcc.5b05296

URL : https://hal.archives-ouvertes.fr/hal-01476148

M. Wang, P. Shim, and . Guyot-sionnest, Electrochromic Nanocrystal Quantum Dots, Science, vol.291, issue.5512, p.2390, 2001.
DOI : 10.1126/science.291.5512.2390