Tuning Solute-Redistribution Dynamics for Scalable Fabrication of Colloidal Quantum-Dot Optoelectronics.

Abstract
Solution-processed colloidal quantum dots (CQDs) are attractive materials for the realization of low-cost and efficient optoelectronic devices. Although impressive CQD-solar-cell performance has been achieved, the fabrication of CQD films is still limited to laboratory-scale small areas because of the complicated deposition of CQD inks. Large-area, uniform deposition of lead sulfide (PbS) CQD inks is successfully realized for photovoltaic device applications by engineering the solute redistribution of CQD droplets. It is shown experimentally and theoretically that the solute-redistribution dynamics of CQD droplets are highly dependent on the movement of the contact line and on the evaporation kinetics of the solvent. By lowering the friction constant of the contact line and increasing the evaporation rate of the droplets, a uniform deposition of CQD ink in length and width over large areas is realized. By utilizing a spray-coating process, large-area (up to 100 cm2 ) CQD films are fabricated with 3-7% thickness variation on various substrates including glass, indium tin oxide glass, and polyethylene terephthalate. Furthermore, scalable fabrication of CQD solar cells is demonstrated with 100 cm2 CQD films which exhibits a notably high efficiency of 8.10%.

Citation
Choi, M., Kim, Y., Lim, H., Alarousu, E., Adhikari, A., Shaheen, B. S., … Jung, Y. S. (2019). Tuning Solute-Redistribution Dynamics for Scalable Fabrication of Colloidal Quantum-Dot Optoelectronics. Advanced Materials, 1805886. doi:10.1002/adma.201805886

Acknowledgements
M.-J.C. and Y.K. contributed equally to this work. This work was supported by the National Research Foundation of Korea (NRF) funded by the Korea government (MSIT) (NRF-2017R1A2B2009948 and NRF-2016M3D1A1900035). This work was also supported by the KIST Institutional Program (2E27301).

Publisher
Wiley

Journal
Advanced materials (Deerfield Beach, Fla.)

DOI
10.1002/adma.201805886
10.1002/adma.201970225

Additional Links
https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201805886

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