Hot-electron transfer in quantum-dot heterojunction films
Tóm tắt
Thermalization losses limit the photon-to-power conversion of solar cells at the high-energy side of the solar spectrum, as electrons quickly lose their energy relaxing to the band edge. Hot-electron transfer could reduce these losses. Here, we demonstrate fast and efficient hot-electron transfer between lead selenide and cadmium selenide quantum dots assembled in a quantum-dot heterojunction solid. In this system, the energy structure of the absorber material and of the electron extracting material can be easily tuned via a variation of quantum-dot size, allowing us to tailor the energetics of the transfer process for device applications. The efficiency of the transfer process increases with excitation energy as a result of the more favorable competition between hot-electron transfer and electron cooling. The experimental picture is supported by time-domain density functional theory calculations, showing that electron density is transferred from lead selenide to cadmium selenide quantum dots on the sub-picosecond timescale.
Từ khóa
Tài liệu tham khảo
Brus, L. E. Electron-electron and electron-hole interactions in small semiconductor crystallites: the size dependence of the lowest excited electronic state. J. Chem. Phys. 80, 4403 (1984).
Banin, U., Cao, Y. W., Katz, D. & Millo, O. Identification of atomic-like electronic states in indium arsenide nanocrystal quantum dots. Nature 400, 542–544 (1999).
Pandey, A. & Guyot-Sionnest, P. Slow electron cooling in colloidal quantum dots. Science 322, 929–932 (2008).
Klimov, V. I. Detailed-balance power conversion limits of nanocrystal-quantum-dot solar cells in the presence of carrier multiplication. Appl. Phys. Lett. 89, 123118 (2006).
Cooney, R. R. et al. Breaking the phonon bottleneck for holes in semiconductor quantum dots. Phys. Rev. Lett. 98, 177403 (2007).
Kambhampati, P. Hot exciton relaxation dynamics in semiconductor quantum dots: radiationless transitions on the nanoscale. J. Phys. Chem. C. 115, 22089–22109 (2011).
Ross, R. T. & Nozik, A. J. Efficiency of hot-carrier solar energy converters. J. Appl. Phys. 53, 3813–3818 (1982).
Guyot-Sionnest, P., Wehrenberg, B. & Yu, D. Intraband relaxation in CdSe nanocrystals and the strong influence of the surface ligands. J. Chem. Phys. 123, 074709 (2005).
Gao, Y. et al. Enhanced hot-carrier cooling and ultrafast spectral diffusion in strongly coupled PbSe quantum-dot solids. Nano. Lett. 11, 5471–5476 (2011).
Tisdale, W. A. et al. Hot-electron transfer from semiconductor nanocrystals. Science 328, 1543–1547 (2010).
Robel, I., Kuno, M. & Kamat, P. V. Size-dependent electron injection from excited CdSe quantum dots into TiO2 nanoparticles. J. Am. Chem. Soc. 129, 4136–4137 (2007).
Li, M. et al. Slow cooling and highly efficient extraction of hot carriers in colloidal perovskite nanocrystals. Nat. Commun. 8, 14350 (2017).
Pandey, A. & Guyot-Sionnest, P. Hot electron extraction from colloidal quantum dots. J. Phys. Chem. Lett. 1, 45–47 (2010).
Sewall, S. L. et al. State-resolved studies of biexcitons and surface trapping dynamics in semiconductor quantum dots. J. Chem. Phys. 129, 084701 (2008).
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. 134, 094706 (2011).
Law, M. et al. Structural, optical, and electrical properties of PbSe nanocrystal solids treated thermally or with simple amines. J. Am. Chem. Soc. 130, 5974–5985 (2008).
Luther, J. M. et al. Structural, optical and electrical properties of self-assembled films of PbSe nanocrystals treated with 1,2-ethanedithiol. ACS Nano 2, 271–280 (2008).
Boehme, S. C. et al. In situ spectroelectrochemical determination of energy levels and energy level offsets in quantum-dot heterojunctions. J. Phys. Chem. C. 120, 5164–5173 (2016).
Klimov, V. I. Optical nonlinearities and ultrafast carrier dynamics in semiconductor nanocrystals. J. Phys. Chem. B 104, 6112–6123 (2000).
Klimov, V. I., McBranch, D. W., Leatherdale, C. A. & Bawendi, M. G. Electron and hole relaxation pathways in semiconductor quantum dots. Phys. Rev. B 60, 13740–13749 (1999).
Sewall, S. L. et al. State-to-state exciton dynamics in semiconductor quantum dots. Phys. Rev. B 74, 235328 (2006).
Fan, F. et al. Continuous-wave lasing in colloidal quantum dot solids enabled by facet-selective epitaxy. Nature 544, 75–79 (2017).
Geiregat, P. et al. Coulomb shifts upon exciton addition to photoexcited PbS colloidal quantum dots. J. Phys. Chem. C 118, 22284–22290 (2014).
Kambhampati, P. Multiexcitons in semiconductor nanocrystals: a platform for optoelectronics at high carrier concentration. J. Phys. Chem. Lett. 3, 1182–1190 (2012).
Alimoradi Jazi, M. et al. Transport properties of a two-dimensional PbSe square superstructure in an electrolyte-gated transistor. Nano. Lett. 17, 5238–5243 (2017).
Empedocles, S. A. & Bawendi, M. G. Quantum-confined stark effect in single CdSe nanocrystallite quantum dots. Science 278, 2114–2117 (1997).
Trinh, M. T. et al. Nature of the second optical transition in PbSe nanocrystals. Nano. Lett. 8, 2112–2117 (2008).
Boehme, S. C. et al. Electrochemical control over photoinduced electron transfer and trapping in CdSe-CdTe quantum-dot solids. ACS Nano 8, 7067–7077 (2014).
De Geyter, B. et al. Broadband and picosecond intraband absorption in lead-based colloidal quantum dots. ACS Nano 6, 6067–6074 (2012).
Spoor, F. C. et al. Hole cooling is much faster than electron cooling in PbSe quantum dots. ACS Nano 10, 695–703 (2016).
Guyot-Sionnest, P., Shim, M., Matranga, C. & Hines, M. Intraband relaxation in CdSe quantum dots. Phys. Rev. B 60, R2181–R2184 (1999).
Gao, Y. et al. Disorder strongly enhances Auger recombination in conductive quantum-dot solids. Nat. Commun. 4, 2329 (2013).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Azpiroz, J. M., Ugalde, J. M. & Infante, I. Benchmark assessment of density functional methods on group II-VI MX (M=Zn, Cd; X=S, Se, Te) quantum dots. J. Chem. Theory Comput. 10, 76–89 (2014).
Hutter, J., Iannuzzi, M., Schiffmann, F. & VandeVondele, J. cp2k:atomistic simulations of condensed matter systems. Wiley Interdiscip. Rev. 4, 15–25 (2014).
Kroeze, J. E. et al. Alkyl chain barriers for kinetic optimization in dye-sensitized solar cells. J. Am. Chem. Soc. 128, 16376–16383 (2006).
van Embden, J. & Mulvaney, P. Nucleation and growth of CdSe nanocrystals in a binary ligand system. Langmuir 21, 10226–10233 (2005).
Steckel, J. S., Yen, B. K., Oertel, D. C. & Bawendi, M. G. On the mechanism of lead chalcogenide nanocrystal formation. J. Am. Chem. Soc. 128, 13032–13033 (2006).
Moreels, I. et al. Composition and size-dependent extinction coefficient of colloidal PbSe quantum dots. Chem. Mater. 19, 6101–6106 (2007).
Jasieniak, J. et al. Re-examination of the size-dependent absorption properties of CdSe quantum dots. J. Phys. Chem. C 113, 19468–19474 (2009).
Craig, C. F., Duncan, W. R. & Prezhdo, O. V. Trajectory surface hopping in the time-dependent Kohn-Sham approach for electron-nuclear dynamics. Phys. Rev. Lett. 95, 163001 (2005).
Akimov, A. V. & Prezhdo, O. V. The PYXAID program for non-adiabatic molecular dynamics in condensed matter systems. J. Chem. Theory Comput. 9, 4959–4972 (2013).
Akimov, A. V. & Prezhdo, O. V. Advanced capabilities of the PYXAID program: integration schemes, decoherence effects, multiexcitonic states, and field-matter interaction. J. Chem. Theory Comput. 10, 789–804 (2014).
Meek, G. A. & Levine, B. G. Evaluation of the time-derivative coupling for accurate electronic state transition probabilities from numerical simulations. J. Phys. Chem. Lett. 5, 2351–2356 (2014).
Fernandez-Alberti, S. et al. Shishiodoshi unidirectional energy transfer mechanism in phenylene ethynylene dendrimers. J. Chem. Phys. 137, 22A526 (2012).
Akimov, A. V. & Prezhdo, O. V. in Encyclopedia of Nanotechnology, Theory of Nonadiabatic Electron Dynamics in Nanomaterials (ed. Bhushan, B.) 1–20. (Springer, Netherlands, 2014).