A printed hybrid warm white light source : from fabrication to physics-based model
With the emerging of printed flexible and stretchable devices, a warm white light source is desirable to minimize the ecological impacts and human health issues brought by light emitting diodes (LEDs). Drop casting, wet stamping and bar coating processes together with screen printing technique are i...
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| Format: | Theses and Dissertations |
| Language: | English |
| Published: |
2017
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| Online Access: | http://hdl.handle.net/10356/72456 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | With the emerging of printed flexible and stretchable devices, a warm white light source is desirable to minimize the ecological impacts and human health issues brought by light emitting diodes (LEDs). Drop casting, wet stamping and bar coating processes together with screen printing technique are implemented to fabricate AC powder electroluminescent (ACPEL) devices hybrid with a layer of organic downshifting dyes. With the optimization of process conditions and design of experiments on solution formulation, a warm white hybrid light source with CCT of 2820 K and luminance of 72.28 cd/m2 is achieved. However, the warm white hybrid ACPEL devices have a luminous efficacy of only 0.5 lm/W. ZnS phosphor level and device level models on charge transport, relaxation and accumulation mechanisms are constructed to explain the observed low luminous efficacy. |
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