Distributed Feedback Lasers Based on Phase-Stabilized CsPbI₃ Thin Films

All-inorganic cesium lead halide perovskites (CsPbX₃, X = I, Br, Cl) are gaining significant attention for their use in light-emitting diodes and lasers, owing to their enhanced thermal stability compared to organic-inorganic hybrid perovskites. While CsPbBr₃ has been extensively studied for stimulated emission and lasing^[1], CsPbI₃ has not received the same level of attention despite its favorable optical properties, with a band gap of about 1.7 eV and emission in the red spectral region. The phase instability of CsPbI₃ causes it to assume a non-perovskite phase (yellow phase) at room temperature, which limits its practical application in devices.<br/>In this presentation, we introduce the first distributed feedback (DFB) lasers utilizing CsPbI₃ thin films, featuring a resonator directly patterned into the perovskite. The additive polyvinylpyrrolidone (PVP) is employed to stabilize the CsPbI₃ thin film in the black phase at room temperature. Previously, we could show that various halide perovskites can be patterned by thermal nanoimprint^[2,3]. Here, we use thermal nanoimprint to pattern second order DFB gratings directly into the perovskite active layer. The γ-CsPbI₃ phase stabilized by PVP remained stable during thermal nanoimprinting at temperatures up to 170°C. Our DFB lasers demonstrate a low lasing threshold of 45 μJ cm^-2 at room temperature under picosecond pulse laser excitation, with tunable emission in the deep red spectral range from 714.1 nm to 723.4 nm^[⁴^]_.Additionally, as a further laser application of our phase-stabilized CsPbI₃ thin films, vertical cavity surface emitting lasers (VCSELs) fabricated utilizing the versatility of thermal nanoimprinting in laser device fabrication and their laser characteristics will be presented.<br/>We expect that our results will have significant implications for the development of future electrically driven perovskite lasers and light-emitting diodes (LEDs) that use CsPbI₃ as the active medium.<br/><br/>[1] N. Pourdavoud <i>et. al.</i>, <i>Adv. Mater.</i> 2019, 31, 1903717<br/>[2] N. Pourdavoud <i>et. al,</i>. <i>Adv. Mater.</i> 2017, 29, 1605003<br/>[3] N. Pourdavoud <i>et. al,</i>. <i>Adv. Mater. Technol.</i> 2018, 3, 1700253<br/>[4] N. Kurahashi <i>et. al</i>, <i>Adv. Funct. Mater.</i> 2024, 2405976