@article {49451, title = {Ultrabroad near infrared emitting perovskites}, journal = {Angewandte Chemie-International Edition}, year = {2024}, month = {SEP}, type = {Article}, abstract = {

Phosphor converted light emitting diodes (pc-LEDs) have revolutionized solid-state white lighting by replacing energy-inefficient filament-based incandescent lamps. However, such a pc-LED emitting ultrabroad near-infrared (NIR) radiations still remains a challenge, primarily because of the lack of ultrabroad NIR emitting phosphors. To address this issue, we have prepared 2.5 \% W4+-doped and 2.8 \% Mo4+-doped Cs2Na0.95Ag0.05BiCl6\ perovskites emitting ultrabroad NIR radiation with unprecedented spectral widths of 434 and 468 nm, respectively. Upon band-edge excitation, the soft lattice of the host exhibits broad self-trapped exciton (STE) emission covering NIR-I (700 nm), which then nonradiatively excites the dopants. The\ mathematical equation\ {\textendash}donor ligand Cl-\ reduces the energy of dopant\ d{\textendash}d\ transitions emitting NIR-II with a peak at ~950 nm. Vibronic coupling broadens the dopant emission. The large spin-orbit coupling and local structural distortion might possibly enhance the dopant emission intensity, leading to an overall NIR photoluminescence quantum yield ~40 \%. The composite of our ultrabroad NIR phosphors with biodegradable polymer polylactic acid could be processed into free-standing films and 3D printed structures. Large (170mathematical equation\ 170 mathematical equation\ ), robust, and thermally stable 3D printed pc-LED panels emit ultrabroad NIR radiation, demonstrating NIR imaging applications.

}, doi = {https://doi.org/10.1002/anie.202415003}, author = {Saikia, Sajid and Gopal, Animesh and Rathod, Radha and Joshi, Aprajita and Priolkar, K. R. and Saha, Surajit and Santra, Pralay K. and Shanmuganathan, Kadhiravan and Nag, Angshuman} }