Alberto Vomiero1

1, Luleå University of Technology, Luleå, , Sweden

Composite quantum dots (QDs) represent the forefront of both fundamental and applied research for smart windows. Specifically, the tunable absorption and emission properties of composite QDs make them ideal candidates for QD-based semitransparent and colored solar cells and luminescent solar concentrators for application in building-integrated photovoltaics.
The optical properties of composite QDs can be finely tuned by proper adjustment of chemical composition, size and morphology of the single components and of the heterostructured systems, including symmetric and asymmetric core-shell and multiple shelled structures.
Key element for light emission is the modulation of the final electronic band structure of the composite, which will tune exciton dynamics in the final system, determining the functionality of the device.
We will illustrate different strategies to obtain the desired optical properties in different complexes to optimize the functionality in specific applications.
A few examples will include: (i) “Giant” composite core-shell QDs, in which modulation of core-to-shell interface induces a single-to double-color photoluminescence; [1-2] (ii) Near-infrared QDs with increased Stokes shift due to suitable electronic structure of the core and shell, to be applied in luminescent solar concentrators [3] and photoelectrochemical systems; [4] (iii) Composite TiO2 mesoporous films sensitized by “giant” and composite QDs with high charge injection from the photoexcited QD to the TiO2 anode, for excitonic solar cells [5] and hydrogen production [6].

[1] G. Sirigu et al. Phys. Rev. B 96, 2017, 155303
[2] H. Zhao et al. Small 12, 2016, 5354
[3] Y. Zhou et al. Adv. En. Mater. 6, 2016, 1501913
[4] L. Jin et al. Nano En. 30, 2016, 531
[5] A. Braga et al. J. Phys. Chem. Lett. 2, 2011, 454
[6] L. Jin et al. Adv. Sci. 3, 2016, 1500345