Probing Ultrafast Excitonic Coherences and Charge-Generation Pathways in Quantum-Dot Photocells via Photocurrent-Detected Two-Dimensional Electronic Spectroscopy.
[en] Understanding how coherent excitonic states influence charge generation is essential for optimizing quantum-dot (QD) optoelectronic devices. Here, we apply photocurrent-detected two-dimensional electronic spectroscopy (PC-2DES) to a functioning CdSe QD photocell to track excitonic interactions and charge-separation dynamics under operational conditions. Selective excitation of the |1S⟩ manifold reveals strong contributions from red-shifted, delocalized excitons that dominate the photocurrent but contribute only weakly in optically detected 2DES. Global analysis uncovers three dynamical components, including a sub-100 fs process associated with photocurrent growth at specific spectral coordinates, consistent with rapid population transfer through delocalized states and possible trion formation. Unlike optical detection, PC-2DES suppresses longitudinal optical phonon signatures, enabling clear observation of higher-frequency beatings attributed to interdot electronic coherences. These results demonstrate the utility of PC-2DES for probing coherent charge-generation pathways in QD solids and for guiding the design of coherence-enabled optoelectronic devices.
Disciplines :
Chemistry
Author, co-author :
Manis Levy, Hadar; Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova 35131, Italy
Doardo, Matilde; Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova 35131, Italy
Hamilton, James ; Université de Liège - ULiège > Département de chimie (sciences) > Laboratoire de chimie physique théorique ; The Fritz Haber Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Dibenedetto, Carlo Nazareno; CNR-IPCF SS Bari, c/o Chemistry Department, University of Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
Degousée, Thibault; School of Physical and Chemical Sciences, Queen Mary University, London E1 4NS, U.K
Mol, Jan A ; School of Physical and Chemical Sciences, Queen Mary University, London E1 4NS, U.K
Striccoli, Marinella; CNR-IPCF SS Bari, c/o Chemistry Department, University of Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
Remacle, Françoise ; Université de Liège - ULiège > Département de chimie (sciences) > Laboratoire de chimie physique théorique ; The Fritz Haber Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Collini, Elisabetta ; Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Padova 35131, Italy
Language :
English
Title :
Probing Ultrafast Excitonic Coherences and Charge-Generation Pathways in Quantum-Dot Photocells via Photocurrent-Detected Two-Dimensional Electronic Spectroscopy.
Publication date :
22 June 2026
Journal title :
ACS Nano
ISSN :
1936-0851
eISSN :
1936-086X
Publisher :
American Chemical Society (ACS), United States
Volume :
ASAP
Peer reviewed :
Peer Reviewed verified by ORBi
Tags :
CÉCI : Consortium des Équipements de Calcul Intensif
MIUR - Ministero dell'Istruzione, dell'Università e della Ricerca Italia. Ministero degli Affari Esteri e della Cooperazione Internazionale F.R.S.-FNRS - Belgian National Fund for Scientific Research European Union
Funding number :
2.5020.11; T.0205.20
Funding text :
CECI Consortium des Equipements de calcul intensif, PDR MONACOMP ■ ACKNOWLEDGMENTS
This work was supported by the National Recovery and
Resilience Plan (NRRP), Mission 4, Component 2, Investment
1.3 Call for Tender No. 1561 of 11.10.2022 of Ministero
dell’Università e della Ricerca (MUR); funded by the
European Union NextGenerationEU, “Network 4 Energy
Sustainable Transition NEST”, Project code PE0000021,
Concession Decree No. 1561 of 11.10.2022, CUP
C93C22005230007. E.C. and H.M.L. acknowledge the support
of the “NV-PC-2DES” Project Accordo Italia-Israele
(MAECI) CUP C93C24006740001. F.R. and J.H.R. acknowledge
the support of the Consortium des Equipements de
Calcul Intensif (CECI), funded by the F.R.S.-FNRS (Fonds
National de la Recherche Scientifique, Belgium) under Grant #2.5020.11 for the computation and the support of F.R.S.-
FNRS through the Grant #T.0205.20. The H2020 FET Project
COPAC (Grant No. 766563) is also acknowledged.
Gill, S. S. et al. Quantum computing: A taxonomy, systematic review and future directions. Software: Pract. Exper. 2022, 52, 66–114, 10.1002/spe.3039
Liu, Y.-C. et al. Quantum integrated sensing and communication via entanglement. Phys. Rev. Appl. 2024, 22, 034051, 10.1103/PhysRevApplied.22.034051
Kagan, C. R.; Lifshitz, E.; Sargent, E. H.; Talapin, D. V. Building devices from colloidal quantum dots. Science 2016, 353 (6302), aac5523, 10.1126/science.aac5523
Collini, E. et al. Quantum Phenomena in Nanomaterials: Coherent Superpositions of Fine Structure States in CdSe Nanocrystals at Room Temperature. J. Phys. Chem. C 2019, 123, 31286–31293, 10.1021/acs.jpcc.9b11153
Collini, E. et al. Room-Temperature Inter-Dot Coherent Dynamics in Multilayer Quantum Dot Materials. J. Phys. Chem. C 2020, 124, 16222–16231, 10.1021/acs.jpcc.0c05572
Kagan, C. R.; Murray, C. B. Charge transport in strongly coupled quantum dot solids. Nat. Nanotechnol. 2015, 10, 1013–1026, 10.1038/nnano.2015.247
Hamilton, J. R.; Amarotti, E.; Dibenedetto, C. N.; Striccoli, M.; Levine, R. D.; Collini, E.; Remacle, F. Harvesting a Wide Spectral Range of Electronic Coherences with Disordered Quasi-Homo Dimeric Assemblies at Room Temperature. Adv. Quantum Technol. 2022, 5 (11), 2200060, 10.1002/qute.202200060
Collini, E. 2D Electronic Spectroscopic Techniques for Quantum Technology Applications. J. Phys. Chem. C 2021, 125, 13096–13108, 10.1021/acs.jpcc.1c02693
Fresch, E.; Camargo, F. V. A.; Shen, Q.; Bellora, C. C.; Pullerits, T.; Engel, G. S.; Cerullo, G.; Collini, E. et al. Two-dimensional electronic spectroscopy. Nat. Rev. Methods Primers 2023, 3 (1), 84, 10.1038/s43586-023-00267-2
Fridman, H. T. et al. Ultrafast Coherent Delocalization Revealed in Multilayer QDs under a Chiral Potential. J. Phys. Chem. Lett. 2023, 14, 2234–2240, 10.1021/acs.jpclett.2c03743
Collini, E.; Gattuso, H.; Levine, R. D.; Remacle, F. Ultrafast fs coherent excitonic dynamics in CdSe quantum dots assemblies addressed and probed by 2D electronic spectroscopy. J. Chem. Phys. 2021, 154 (1), 014301, 10.1063/5.0031420
Hamilton, J. R. et al. Time–Frequency Signatures of Electronic Coherence of Colloidal CdSe Quantum Dot Dimer Assemblies Probed at Room Temperature by Two-Dimensional Electronic Spectroscopy. Nanomaterials 2023, 13, 2096, 10.3390/nano13142096
Tekavec, P. F.; Lott, G. A.; Marcus, A. H. Fluorescence-detected two-dimensional electronic coherence spectroscopy by acousto-optic phase modulation. J. Chem. Phys. 2007, 127 (21), 214307, 10.1063/1.2800560
Damtie, F. A.; Wacker, A.; Pullerits, T.; Karki, K. J. Two-dimensional action spectroscopy of excitonic systems: Explicit simulation using a phase-modulation technique. Phys. Rev. A 2017, 96, 053830, 10.1103/PhysRevA.96.053830
Kühn, O.; Mančal, T.; Pullerits, T. Interpreting Fluorescence Detected Two-Dimensional Electronic Spectroscopy. J. Phys. Chem. Lett. 2020, 11, 838–842, 10.1021/acs.jpclett.9b03851
Nardin, G. Multidimensional coherent optical spectroscopy of semiconductor nanostructures: a review. Semicond. Sci. Technol. 2016, 31, 023001, 10.1088/0268-1242/31/2/023001
Bakulin, A. A.; Silva, C.; Vella, E. Ultrafast Spectroscopy with Photocurrent Detection: Watching Excitonic Optoelectronic Systems at Work. J. Phys. Chem. Lett. 2016, 7, 250–258, 10.1021/acs.jpclett.5b01955
Nardin, G.; Autry, T. M.; Silverman, K. L.; Cundiff, S. T. Multidimensional coherent photocurrent spectroscopy of a semiconductor nanostructure. Opt. Express 2013, 21, 28617, 10.1364/OE.21.028617
Bruschi, M.; Gallina, F.; Fresch, B. Simulating action-2D electronic spectroscopy of quantum dots: insights on the exciton and biexciton interplay from detection-mode and time-gating. Phys. Chem. Chem. Phys. 2022, 24, 27645–27659, 10.1039/D2CP04270C
Roeding, S.; Brixner, T. Coherent two-dimensional electronic mass spectrometry. Nat. Commun. 2018, 9 (1), 2519, 10.1038/s41467-018-04927-w
Casotto, A. et al. Coherent Vibrations Promote Charge-Transfer across a Graphene-Based Interface. J. Am. Chem. Soc. 2024, 146, 14989–14999, 10.1021/jacs.3c12705
Bolzonello, L. et al. Photocurrent-Detected 2D Electronic Spectroscopy Reveals Ultrafast Hole Transfer in Operating PM6/Y6 Organic Solar Cells. J. Phys. Chem. Lett. 2021, 12, 3983–3988, 10.1021/acs.jpclett.1c00822
López-Ortiz, M. et al. Photoelectrochemical Two-Dimensional Electronic Spectroscopy (PEC2DES) of Photosystem I: Charge Separation Dynamics Hidden in a Multichromophoric Landscape. ACS Appl. Mater. Interfaces 2024, 16, 43451–43461, 10.1021/acsami.4c03652
Karki, K. J. et al. Coherent two-dimensional photocurrent spectroscopy in a PbS quantum dot photocell. Nat. Commun. 2014, 5, 5869, 10.1038/ncomms6869
Leatherdale, C. A. et al. Photoconductivity in CdSe quantum dot solids. Phys. Rev. B 2000, 62, 2669–2680, 10.1103/PhysRevB.62.2669
Morgan, N. Y. et al. Electronic transport in films of colloidal CdSe nanocrystals. Phys. Rev. B 2002, 66, 075339, 10.1103/PhysRevB.66.075339
Zhang, M. et al. Accounting for pulse shaper nonlinearity in action-detected two-dimensional electronic spectroscopy. Opt. Express 2025, 33, 52793, 10.1364/OE.580416
Yu, W. W.; Qu, L.; Guo, W.; Peng, X. Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals. Chem. Mater. 2003, 15, 2854–2860, 10.1021/cm034081k
Zhang, Z. et al. Ultrafast exciton transport at early times in quantum dot solids. Nat. Mater. 2022, 21, 533–539, 10.1038/s41563-022-01204-6
Perdomo-Ortiz, A.; Widom, J. R.; Lott, G. A.; Aspuru-Guzik, A.; Marcus, A. H. Conformation and Electronic Population Transfer in Membrane-Supported Self-Assembled Porphyrin Dimers by 2D Fluorescence Spectroscopy. J. Phys. Chem. B 2012, 116, 10757–10770, 10.1021/jp305916x
Malý, P.; Mančal, T. Signatures of Exciton Delocalization and Exciton–Exciton Annihilation in Fluorescence-Detected Two-Dimensional Coherent Spectroscopy. J. Phys. Chem. Lett. 2018, 9, 5654–5659, 10.1021/acs.jpclett.8b02271
Schröter, M.; Pullerits, T.; Kühn, O. Using fluorescence detected two-dimensional spectroscopy to investigate initial exciton delocalization between coupled chromophores. J. Chem. Phys. 2018, 149 (11), 114107, 10.1063/1.5046645
Kunsel, T. et al. Simulating Fluorescence-Detected Two-Dimensional Electronic Spectroscopy of Multichromophoric Systems. J. Phys. Chem. B 2019, 123, 394–406, 10.1021/acs.jpcb.8b10176
Grégoire, P.; Srimath Kandada, A. R.; Vella, E.; Tao, C.; Leonelli, R.; Silva, C. et al. Incoherent population mixing contributions to phase-modulation two-dimensional coherent excitation spectra. J. Chem. Phys. 2017, 147 (11), 114201, 10.1063/1.4994987
Bruschi, M.; Bolzonello, L.; Gallina, F.; Fresch, B. Unifying Nonlinear Response and Incoherent Mixing in Action-2D Electronic Spectroscopy. J. Phys. Chem. Lett. 2023, 14, 6872–6879, 10.1021/acs.jpclett.3c01670
Bruschi, M.; Zambon, R.; Gallina, F.; Fresch, B. Influence of excitonic coupling, static disorder, and coherent dynamics in action-2D electronic spectroscopy of a molecular dimer model. J. Chem. Phys. 2025, 163 (8), 084113, 10.1063/5.0276191
Volpato, A.; Bolzonello, L.; Meneghin, E.; Collini, E. Global analysis of coherence and population dynamics in 2D electronic spectroscopy. Opt. Express 2016, 24, 24773, 10.1364/OE.24.024773
Karki, K. J. et al. Before Förster. Initial excitation in photosynthetic light harvesting. Chem. Sci. 2019, 10, 7923–7928, 10.1039/C9SC01888C
Malý, P. et al. Coherently and fluorescence-detected two-dimensional electronic spectroscopy: direct comparison on squaraine dimers. Phys. Chem. Chem. Phys. 2020, 22, 21222–21237, 10.1039/D0CP03218B
Fresch, E. et al. How the Protein Environment Can Tune the Energy, the Coupling, and the Ultrafast Dynamics of Interacting Chlorophylls: The Example of the Water-Soluble Chlorophyll Protein. J. Phys. Chem. Lett. 2020, 11, 1059–1067, 10.1021/acs.jpclett.9b03628
Marcolin, G. et al. Two-Dimensional Electronic Spectroscopy Characterization of Fucoxanthin–Chlorophyll Protein Reveals Excitonic Carotenoid–Chlorophyll Interactions. J. Phys. Chem. Lett. 2024, 15, 2392–2399, 10.1021/acs.jpclett.3c03609
Righetto, M. et al. Deciphering hot- and multi-exciton dynamics in core–shell QDs by 2D electronic spectroscopies. Phys. Chem. Chem. Phys. 2018, 20, 18176–18183, 10.1039/C8CP02574F
Klimov, V. I.; McBranch, D. W.; Leatherdale, C. A.; Bawendi, M. G. Electron and hole relaxation pathways in semiconductor quantum dots. Phys. Rev. B 1999, 60, 13740–13749, 10.1103/PhysRevB.60.13740
Sewall, S. L.; Cooney, R. R.; Anderson, K. E. H.; Dias, E. A.; Kambhampati, P. State-to-state exciton dynamics in semiconductor quantum dots. Phys. Rev. B 2006, 74, 235328, 10.1103/PhysRevB.74.235328
Sewall, S. L.; Cooney, R. R.; Anderson, K. E. H.; Dias, E. A.; Sagar, D. M.; Kambhampati, P. et al. State-resolved studies of biexcitons and surface trapping dynamics in semiconductor quantum dots. J. Chem. Phys. 2008, 129 (8), 084701, 10.1063/1.2971181
Tyagi, P.; Kambhampati, P. False multiple exciton recombination and multiple exciton generation signals in semiconductor quantum dots arise from surface charge trapping. J. Chem. Phys. 2011, 134 (9), 094706, 10.1063/1.3561063
Saari, J. I. et al. Ultrafast Electron Trapping at the Surface of Semiconductor Nanocrystals: Excitonic and Biexcitonic Processes. J. Phys. Chem. B 2013, 117, 4412–4421, 10.1021/jp307668g
Klimov, V.; Hunsche, S.; Kurz, H. Biexciton effects in femtosecond nonlinear transmission of semiconductor quantum dots. Phys. Rev. B 1994, 50, 8110–8113, 10.1103/PhysRevB.50.8110
Huang, J. et al. Enhanced Photocurrent and Electrically Pumped Quantum Dot Emission from Single Plasmonic Nanoantennas. ACS Nano 2024, 18, 3323–3330, 10.1021/acsnano.3c10092
Klimov, V. I. Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Nanocrystals. J. Phys. Chem. B 2000, 104, 6112–6123, 10.1021/jp9944132
Seiler, H.; Palato, S.; Sonnichsen, C.; Baker, H.; Kambhampati, P. Seeing Multiexcitons through Sample Inhomogeneity: Band-Edge Biexciton Structure in CdSe Nanocrystals Revealed by Two-Dimensional Electronic Spectroscopy. Nano Lett. 2018, 18, 2999–3006, 10.1021/acs.nanolett.8b00470
Zhang, Y.; Oh, S.; Alharbi, F. H.; Engel, G. S.; Kais, S. Delocalized quantum states enhance photocell efficiency. Phys. Chem. Chem. Phys. 2015, 17, 5743–5750, 10.1039/C4CP05310A
Reid, W. M.; Driscoll, T.; Doty, M. F. Forming delocalized intermediate states with realistic quantum dots. J. Appl. Phys. 2012, 111 (5), 056102, 10.1063/1.3691113
Bakulin, A. A. et al. The Role of Driving Energy and Delocalized States for Charge Separation in Organic Semiconductors. Science 2012, 335, 1340–1344, 10.1126/science.1217745
Singh, A. et al. Trion formation dynamics in monolayer transition metal dichalcogenides. Phys. Rev. B 2016, 93, 041401, 10.1103/PhysRevB.93.041401
Kossacki, P. et al. Formation Time of Negatively Charged Excitons in CdTe-Based Quantum Wells. Phys. Status Solidi B 2002, 229, 659–663, 10.1002/1521-3951(200201)229:2<659::AID-PSSB659>3.0.CO;2-S
Lampert, M. A. Mobile and Immobile Effective-Mass-Particle Complexes in Nonmetallic Solids. Phys. Rev. Lett. 1958, 1, 450–453, 10.1103/PhysRevLett.1.450
Kheng, K. et al. Observation of negatively charged excitons X – in semiconductor quantum wells. Phys. Rev. Lett. 1993, 71, 1752–1755, 10.1103/PhysRevLett.71.1752
Climente, J. I.; Bertoni, A.; Goldoni, G. Photoluminescence spectroscopy of trions in quantum dots: A theoretical description. Phys. Rev. B 2008, 78, 155316, 10.1103/PhysRevB.78.155316
Ganchev, B.; Drummond, N.; Aleiner, I.; Fal’ko, V. Three-Particle Complexes in Two-Dimensional Semiconductors. Phys. Rev. Lett. 2015, 114, 107401, 10.1103/PhysRevLett.114.107401
Melnychuk, C.; Guyot-Sionnest, P. Multicarrier Dynamics in Quantum Dots. Chem. Rev. 2021, 121, 2325–2372, 10.1021/acs.chemrev.0c00931
Peng, L. et al. Bright trion emission from semiconductor nanoplatelets. Phys. Rev. Mater. 2020, 4, 056006, 10.1103/PhysRevMaterials.4.056006
Honarfar, A. et al. Photoexcitation Dynamics in Electrochemically Charged CdSe Quantum Dots: From Hot Carrier Cooling to Auger Recombination of Negative Trions. ACS Appl. Energy Mater. 2020, 3, 12525–12531, 10.1021/acsaem.0c02478
Shimizu, K. T.; Woo, W. K.; Fisher, B. R.; Eisler, H. J.; Bawendi, M. G. Surface-Enhanced Emission from Single Semiconductor Nanocrystals. Phys. Rev. Lett. 2002, 89, 117401, 10.1103/PhysRevLett.89.117401
Seibt, J.; Pullerits, T. Beating Signals in 2D Spectroscopy: Electronic or Nuclear Coherences? Application to a Quantum Dot Model System. J. Phys. Chem. C 2013, 117, 18728–18737, 10.1021/jp406103m
Seibt, J.; Hansen, T.; Pullerits, T. 3D Spectroscopy of Vibrational Coherences in Quantum Dots: Theory. J. Phys. Chem. B 2013, 117, 11124–11133, 10.1021/jp4011444
Palato, S.; Seiler, H.; Nijjar, P.; Prezhdo, O.; Kambhampati, P. Atomic fluctuations in electronic materials revealed by dephasing. Proc. Natl. Acad. Sci. U. S. A. 2020, 117, 11940–11946, 10.1073/pnas.1916792117
Volpato, A.; Collini, E. Optimization and selection of time-frequency transforms for wave-packet analysis in ultrafast spectroscopy. Opt. Express 2019, 27, 2975, 10.1364/OE.27.002975
Volpato, A.; Collini, E. Time-frequency methods for coherent spectroscopy. Opt. Express 2015, 23, 20040, 10.1364/OE.23.020040
Dibenedetto, C. N. et al. Coupling effects in QD dimers at sub-nanometer interparticle distance. Nano Res. 2020, 13, 1071–1080, 10.1007/s12274-020-2747-3
Dibenedetto, C. N. et al. Coupling in quantum dot molecular hetero-assemblies. Mater. Res. Bull. 2022, 146, 111578, 10.1016/j.materresbull.2021.111578
