Recyclable flame retardant, luminescent, and transparent thermoplastic polyurethanes: applications in light conversion films for flexible solar cells

With the development of new energy industry and the promulgation of environmental protection decrees, synthesize the recyclable, high performance functional polymers is becoming particularly important. Here, a multifunctional flame retardant NEDP was designed, and the recyclable TPU-DP composites prepared with NEDP, which had excellent flame retardancy, luminescence, mechanical properties and transparency. With the addition of 9 % NEDP, the TPU-DP composite successfully passed the UL-94 V-0 rating and the Limiting oxygen index (LOI) value increased to 30.3 %. Besides, the TPU-DP present excellent photoluminescent properties, emits visible blue fluorescence under UV excitation, and maintains >80 % light transmission. What's more, the TPU-DP composite also maintains good mechanical properties and recyclability, which is conducive to sustainable development. Mechanistic studies indicate that the excellent flame retardancy of NEDP credit due to the combined effect of the carbonization layer barrier in the condense phase and the flame burst in the gas phase. We apply it in flexible solar cell film, which improves the fire safety of flexible solar cells and protects the cells from external damages, and the recyclability ensures the sustainable development of the green industry. More importantly, using the luminous TPU-DP film, the photovoltaic conversion efficiency of flexible solar cells increased by 0.8 %, making up for the shortcomings of the photovoltaic conversion efficiency of flexible solar cells. Thus, the TPU-DP composites are expected to promote the green and sustainable development of modern energy industry, and have significant commercial value and theoretical significance.