Nano Bulk Heterojunction Ensemble for Highly Efficient Optical Downconverters

Sarjeet Kumar^a, Santanu Pradhan^a

^aCentre for Nanotechnology, Indian Institute of Technology (IIT) Roorkee, Uttarakhand, India (247667)

Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)

D3 Chalcogenide Quantum Dots: Materials and Devices for Infrared Light Harvesting, Sensing and Emission

Barcelona, Spain, 2026 March 23rd - 27th

Organizer: Yongjie Wang

Poster, Sarjeet Kumar, 733
Publication date: 15th December 2025

The easy and cost-effective solution-based synthesis, size-tunable optoelectronic properties, large exciton Bohr radius, tunable surface chemistry, and strong near infrared (IR) emission of lead sulfide (PbS) colloidal quantum dots (CQDs) are making them an ideal candidate for several applications, such as IR light-emitting diodes, photosensors, photoconverters, etc. The emission properties of PbS QDs can be significantly enhanced by mixing an optimized amount of PbS QDs with a higher bandgap matrix material.^1,2 The position of energy levels, absorption coefficient, mobility, and carrier diffusion length of the matrix material play a crucial role in charge/energy transferring from the matrix to the emitter PbS QDs. Here, we improved the emission of PbS QDs by incorporating them inside the CsPbBr₃ nanocrystal (NC) matrix. A simple, room temperature method was used to form the PbS- CsPbBr₃heterostructure. The higher diffusion length, easy solution processability, improved environmental stability, good lattice matching, and suitable band position of CsPbBr₃ NC-matrix³ helped improve the energy/charge funneling to the PbS QDs, and thus their emission intensity was enhanced. The PbS-CsPbBr₃ NC mixture was used for the optical down conversion of the visible light to the IR light. Broadband and flexible optical downconverters were fabricated by mixing different types of emitter PbS QDs with the CsPbBr₃matrix. These broadband downconverters served as the broadband NIR source for the spectroscopic applications. Further, these downconverters were integrated with the commercially available InGaAs photodetectors to improve their visible detection capability.

References:

[1] Pradhan, S.; Dalmases, M.; Konstantatos, G. Solid-State Thin-Film Broadband Short-Wave Infrared Light Emitters. Advanced Materials 2020, 32 (45), 2003830

[2] Pradhan, S.; Di Stasio, F.; Bi, Y.; Gupta, S.; Christodoulou, S.; Stavrinadis, A.; Konstantatos, G. High-Efficiency Colloidal Quantum Dot Infrared Light-Emitting Diodes via Engineering at the Supra-Nanocrystalline Level. Nat Nanotechnol 2019, 14 (1), 72–79

[3] Kumar, S.; Salunke, A.; Pradhan, S. Achieving Ultra-Stable, Near-Unity Photoluminescence Quantum Yield Under Extreme Humidity and High Electric Field for CsPbBr 3 Nanocrystals Through the Surface Attachment of ZnO Nanoparticles. ACS Applied Optical Materials 2024, 2 (1), 128–138

Acknowledgements:

The author, Mr. Sarjeet Kumar, acknowledges the Ministry of Education, Govt. of India, for the Prime Minister’s Research Fellowship (PMRF) (PMRF-ID, 2803628).

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