Shaping the Photoluminescence of Infrared-Emitting Nanocrystals Through Their Coupling to Photonic Structures

Infrared-active colloidal quantum dots (CQDs) have recently emerged as a powerful alternative to traditional epitaxially grown semiconductors, notably for light emission purposes. While in the visible the potential of CQDs as light emitters has been widely realized and has reached commercial levels of development, further efforts are still needed in the infrared. In particular, their luminescence efficiency tends to drop drastically after device integration.
To remedy this issue, a key component is the efficient extraction of light from devices. In most light-emitting structures, only 20% of generated photons radiate to the outside, due to internal reflections and waveguiding at the different material interfaces. A possible strategy to solve this problem is the coupling of the CQDs’ emission to a photonic structure, enabling control over light-matter interactions inside the device. When properly designed, these interactions can grant directionality to an isotropic emission and in theory ensure the outcoupling of most photons in light-emitting devices.
To demonstrate this strategy, we studied a wide array of infrared-active CQDs. We started from HgTe^1,2, one of the most mature infrared-active CQD materials, and then extended towards heavy-metal-free materials (III-V semiconductors³ and silver chalcogenides⁴) to address toxicity concerns toward future industrial developments.
We demonstrated their successful integration to different photonic structures compatible with future device functionalization, ranging from plasmonic metallic gratings^1,3 to full-dielectric cavities^2,4, through simple solution processing techniques. The resulting coupling led to enhanced luminescence properties from the CQDs, such as a 3-fold increased photoluminescence magnitude¹, a strong directivity down to 15° around normal incidence^2,4, and a decreased spectral linewidth by a factor⁴ of 20. These results highlight the benefits of CQDs for photonics in the infrared and advance the realization of optimized and efficient solution-processed light-emitting devices in the same range.

References:
1. E. Bossavit, T. H. Dang, P. He, M. Cavallo, A. Khalili, C. Dabard, H. Zhang, D. Gacemi, M. G. Silly, C. Abadie, B. Gallas, D. Pierucci, Y. Todorov, C. Sirtori, B. T. Diroll, A. Degiron, E. Lhuillier, A. Vasanelli, Advanced Optical Materials 2023, 11, 2300863.
2. E. Bossavit, H. Zhang, N. Ledos, M. Cavallo, D. Mastrippolito, L. Curti, A. Khalili, A. Colle, P. Lample, M. Weis, F. Margaillan, X. Lafosse, Y. Prado, E. Péronne, D. Pierucci, S. Ithurria, D. Boschetto, B. T. Diroll, A. Degiron, E. Lhuillier, Adv Funct Materials 2024, 2403532.
3. E. Bossavit, O. Yeromina, D. Mastrippolito, M. Cavallo, H. Zhang, T. Gemo, A. Colle, A. Khalili, A. Shcherbakov, L. D. Nguyen, C. Abadie, E. Dandeu, M. G. Silly, B. Gallas, D. Pierucci, A. Degiron, P. Reiss, E. Lhuillier, Advanced Optical Materials n.d., n/a, 2401601.
4. L. Makke, E. Bossavit, D. Mastrippolito, A. Shcherbakov, M. Cavallo, H. Zhang, T. Gemo, A. Colle, A. Khalili, M. Hua, X. Lafosse, X. Z. Xu, M. G. Silly, D. Pierucci, E. Lhuillier, B. T. Diroll, A. Degiron, S. Ithurria, Submitted