Ruoping Li

Mid-infrared pulsed lasers are pivotal for biomedical engineering and atmospheric remote sensing, yet power scaling is severely bottlenecked by poor thermal stability and low damage thresholds of conventional saturable absorbers. Here, we address this limitation through a thermodynamic optimization strategy applied to atomically thin iron-based crystals grown by space-confined chemical vapor deposition. Screening anionic chalcogens (Se, S, and O) paired with Fe identifies iron oxide as the most stable matrix, while Mn doping further stabilizes the matrix and modulates carrier dynamics. Mn incorporation enhances the laser-induced damage threshold approximately 3-fold and accelerates carrier relaxation to 23.63 ps. Consequently, a record-high average output power exceeding 1.0 W was achieved in an Er3+-doped fiber laser at 2.8 μm, accompanied by nanosecond pulse compression and operation stability over 30 days. Our findings establish lattice thermodynamics as a material route to high-energy mid-infrared pulsed lasers and highlight its potential for on-chip long-wave terahertz photonic devices.

High-efficiency antimony sulfide (Sb2S3) solar cells have successfully learned from the device structure of perovskite solar cells and often use spiro-OMeTAD as the hole-transporting layer (HTL). However, the stability of spiro-OMeTAD under an atmospheric environment is poor. It is generally believed that copper-based semiconductor nanocrystals (NCs), demonstrating appropriate valence band maximum (VBM), remarkable stability, and abundant elements, are suitable for the HTLs. In practice, however, related research has mainly focused on perovskite solar cells. In this work, Cu2SnS3, Cu2ZnSnS4, and CuInS2 nanocrystals are synthesized by the hot injection method and successfully used as HTLs in high-efficiency Sb2S3 solar cells. Through hexanethiol ligand exchange, dense and continuous copper-based semiconductor nanocrystal films are prepared by the spin coating method. Furthermore, the device performances of Sb2S3 solar cells based on Cu2SnS3, Cu2ZnSnS4, and CuInS2 HTLs are up to 6.52, 6.70, and 7.06%, respectively. It shows a comparable performance with the traditional spiro-OMeTAD (7.10%) and significantly improved stability compared to the Sb2S3 solar cell based on the spiro-OMeTAD HTL in an air atmosphere. This work highlights the importance of HTL in achieving high-efficiency and stable Sb2S3 optoelectronic devices.

TiO ₂ (rutile–anatase, R–A)/Ti ₃ C ₂ T _x heterophase junction (HPJ)–Schottky junction (SHJ) composites oxidized in situ by Ti ₃ C ₂ T _x MXenes were synthesized via a one-step hydrothermal method using Ti ₃ C ₂ T _x MXenes as the Ti source and water as the solvent.