Perovskite Quantum Dots on Polymer Matrix for Stretchable LED

Most intrinsically stretchable LEDs are developed using a polymer emitting layer, but the organic LED cannot produce vivid colors because of its low color purity with large full width half maximum (FWHM). In the case of organic LED, the FWHM is about 70-90 nm and it achieved 96% of the National Television Standards Committee (NTSC) standard in the Commission Internationale de l'éclairage (CIE) chromaticity chart. However, perovskite quantum dot (QD) LED can produce vivid colors due to its high color purity (low FWHM). The perovskite QD LED has 15~25 nm of FWHM and it achieved 140% of the NTSC standard CIE chromaticity chart. Accordingly, the perovskite QD LEDs can reproduce a vivid image closer to natural color than organic LEDs. Here, we developed an intrinsically stretchable perovskite QD LED by introducing perovskite QD in the semiconducting polymer matrix. The energy band of the polymer matrix must be larger than the energy band of perovskite QD for the energy transfer to perovskite QD. In addition, the polymer matrix has to interact with the perovskite QD physically, so the perovskite QD should be evenly dispersed in the polymer matrix. The stretchable LED was fabricated using the polymer matrix, which had a larger band gap and physical interaction with perovskite QD on the TPU substrate. The fabricated LED could be stretched up to 75% and emitted light under strain with high color purity (~18 nm of FWHM). This intrinsically stretchable LED would be successfully harnessed for stretchable free-form wearable devices, enabling accurate bio-signal analysis and phototherapy for various biomedical applications.