Seminar : Ilka Kriegel (Italian Institute of Technology) – Friday 24 Sept 2021, 11am

Publié le : 24/09/2021

Seminar : Ilka Kriegel (Italian Institute of Technology)

Photodoping of doped metal oxide nanocrystals : towards light-driven energy storage

Friday 24 Sept 2021, 11am (online and in room 32-42.101)


Doped metal oxide nanocrystals (MO NCs), such as Sn doped In2O3 (ITO) or doped zinc oxide (ZnO) and cadmium oxide (CdO) display localized surface plasmon resonances due to their carrier density around 1021 cm-3 [1]. Such optical properties are tunable across the near infrared spectral range upon doping control. The dynamic modulation becomes possible through the pseudo-capacitive charge injection by applying an electrochemical potential or through the interaction with light beyond their bandgap, i.e. photodoping [2–4]. The latter allows accumulation of multiple electrons within one NC through the absorption of several photons, as the holes react with sacrificial hole scavengers (Figure 1). Capacitance values comparable to commercially available supercapacitor materials are extracted [5,6]. In this presentation, I will discuss the fundamental physical and chemical processes underlying photodoping of MO NCs. I will further discuss the possibility of multi-charge transfer processes following photodopin and highlight open questions with regards to their implementation as novel light-driven multi-charge accumulation components in the next generation of solar energy devices [6–8].

Figure 1. Photodoping of doped MO NCs, such as ITO or doped ZnO orCdO NCs. When light with energy beyond the bandgap hits the NC and electron hole pair is created. The hole is removed by reacting with a hole scavenger and in this way the electron is stored in the NC. By absorbing several photons multiple charges are accumulated. Background : typical SEM image of ITO NCs.


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2. Agrawal, A. et al. Rationalizing the Impact of Surface Depletion on Electrochemical Modulation of Plasmon Resonance Absorption in Metal Oxide Nanocrystals. ACS Photonics 5, 2044–2050 (2018).

3. Paternò, G. M. et al. Solution processable and optically switchable 1D photonic structures. Sci. Rep. 8, 3517 (2018).

4. Kriegel, I. et al. Ultrafast Photodoping and Plasmon Dynamics in Fluorine–Indium Codoped Cadmium Oxide Nanocrystals for All-Optical Signal Manipulation at Optical Communication Wavelengths. J. Phys. Chem. Lett. 7, 3873–3881 (2016).

5. Brozek, C. K. et al. Soluble Supercapacitors : Large and Reversible Charge Storage in Colloidal Iron-Doped ZnO Nanocrystals. Nano Lett. 18, 3297–3302 (2018).

6. Kriegel, I. et al. Light-Driven Permanent Charge Separation across a Hybrid Zero-Dimensional/Two-Dimensional Interface. J. Phys. Chem. C 124, 8000–8007 (2020).

7. Ghini, M. et al. Photodoping of metal oxide nanocrystals for multi-charge accumulation and light-driven energy storage. Nanoscale 13, 8773–8783 (2021).

8. Ghini, M. et al. 0D Nanocrystals as Light-Driven, Localized Charge-Injection Sources for the Contactless Manipulation of Atomically Thin 2D Materials. Adv. Photonics Res. 2, 2000151 (2021).