Morphological and Chemical Changes in Cd-free Colloidal QD-LEDs During Operation
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arXiv
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2025
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| author | Zhang, Ruiqi Geng, Jamie Tan, Shaun Srinivasan, Shreyas Kim, Taehyung Saravanapavanantham, Mayuran Lim, Kwang-Hee Dillender, Mike Chung, Heejae Nguyen, Thienan Yang, Karen Lu, Yongli Kim, Taegon Bawendi, Moungi G. Bulovic, Vladimir |
| author_facet | Zhang, Ruiqi Geng, Jamie Tan, Shaun Srinivasan, Shreyas Kim, Taehyung Saravanapavanantham, Mayuran Lim, Kwang-Hee Dillender, Mike Chung, Heejae Nguyen, Thienan Yang, Karen Lu, Yongli Kim, Taegon Bawendi, Moungi G. Bulovic, Vladimir |
| contents | Heavy metal-free quantum-dot light-emitting devices (QD-LEDs) have demonstrated remarkable brightness, saturated color, and high efficiencies across a broad spectral range. However, in contrast to organic LEDs (OLEDs), QD-LED operational lifetimes remain limited, with the underlying degradation mechanisms not fully understood. In the present study, we show that InP/ZnSe/ZnS (red-emitting) and ZnTeSe/ZnSe/ZnS (blue-emitting) cadmium-free colloidal QD-LEDs undergo nanoscale morphological changes during operation. Specifically,interparticle coarsening and layer thinning are observed in the electron transport layer (ETL) consisting of ZnMgO nanoparticles (NPs), in the QD emissive layer, and in the organic hole transport layer. This is accompanied by the generation and diffusion of compositional oxygen- and hydrogen-radicals throughout the device, with oxygen accumulating at the electrode/ETL interfance. Moreover, in situ transmission electron microscopy reveals the electron beam exposure, in the presence of hydrogen radicals, accelerates ZnMgO NPs coarsening. To mitigate these degradation pathway, we show that acrylate-based resin-encapsulation treatment stabilize the ETL/QD layers by suppressing the radical formation and halting morphology changes. This approach achieves dramatic stability enhancements, exhibits an 8-fold and 5000-fold lifetime improvement on InP/ZnSe/ZnS and ZnTeSe/ZnSe/ZnS QD-LEDs, respectively. Our findings establish the causal relationships between the morphological degradation, interlayer radical dynamics, and state-of-the-art QD-LEDs instability, providing new insights into a scalable encapsulation treatment that enables efficient and long-lived Cd-free QD-LEDs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_12597 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Morphological and Chemical Changes in Cd-free Colloidal QD-LEDs During Operation Zhang, Ruiqi Geng, Jamie Tan, Shaun Srinivasan, Shreyas Kim, Taehyung Saravanapavanantham, Mayuran Lim, Kwang-Hee Dillender, Mike Chung, Heejae Nguyen, Thienan Yang, Karen Lu, Yongli Kim, Taegon Bawendi, Moungi G. Bulovic, Vladimir Applied Physics Materials Science Heavy metal-free quantum-dot light-emitting devices (QD-LEDs) have demonstrated remarkable brightness, saturated color, and high efficiencies across a broad spectral range. However, in contrast to organic LEDs (OLEDs), QD-LED operational lifetimes remain limited, with the underlying degradation mechanisms not fully understood. In the present study, we show that InP/ZnSe/ZnS (red-emitting) and ZnTeSe/ZnSe/ZnS (blue-emitting) cadmium-free colloidal QD-LEDs undergo nanoscale morphological changes during operation. Specifically,interparticle coarsening and layer thinning are observed in the electron transport layer (ETL) consisting of ZnMgO nanoparticles (NPs), in the QD emissive layer, and in the organic hole transport layer. This is accompanied by the generation and diffusion of compositional oxygen- and hydrogen-radicals throughout the device, with oxygen accumulating at the electrode/ETL interfance. Moreover, in situ transmission electron microscopy reveals the electron beam exposure, in the presence of hydrogen radicals, accelerates ZnMgO NPs coarsening. To mitigate these degradation pathway, we show that acrylate-based resin-encapsulation treatment stabilize the ETL/QD layers by suppressing the radical formation and halting morphology changes. This approach achieves dramatic stability enhancements, exhibits an 8-fold and 5000-fold lifetime improvement on InP/ZnSe/ZnS and ZnTeSe/ZnSe/ZnS QD-LEDs, respectively. Our findings establish the causal relationships between the morphological degradation, interlayer radical dynamics, and state-of-the-art QD-LEDs instability, providing new insights into a scalable encapsulation treatment that enables efficient and long-lived Cd-free QD-LEDs. |
| title | Morphological and Chemical Changes in Cd-free Colloidal QD-LEDs During Operation |
| topic | Applied Physics Materials Science |
| url | https://arxiv.org/abs/2509.12597 |