Highly Sensitive Narrowband Near-Infrared Photodetectors with Detectivity Exceeding 1013 Jones

Narrowband near-infrared photodetectors (NIRPDs) are significantly cost-effective and have a smaller system volume for various applications. Employing lanthanide-doped upconversion nanoparticles (UCNPs) as near-infrared absorbing photoactive materials is a feasible concept for constructing highly sensitive and stable narrowband NIRPDs, but it is limited by their luminescence efficiency. Herein, the strong UC emission and stability of K+, Sb3+-codoped Cs2NaYb0.85Er0.15Cl6 DPNPs were synthesized using the hot injection method. Compared to the pristine Cs2NaYb0.85Er0.15Cl6 DPNPs, the optimized K+, Sb3+-codoped Cs2NaYb0.85Er0.15Cl6 DPNPs demonstrated a 51.6-fold enhancement and longer lifetime. This improvement can be mainly due to the low phonon energy, fewer trap defects, and high energy transfer efficiency. Finally, we developed triple-band (808, 980, and 1540 nm) narrowband NIRPDs based on the Cs2Na0.9K0.1Yb0.845Er0.15Sb0.005Cl6 DPNPs/ITO/SnO2/MAPbI3/spiro-OMeTAD/Ag device. These narrowband NIRPDs with high performance and rapid response time, showing a detectivity of 2.27 × 1013 Jones at 808 nm, 2.87 × 1013 Jones at 980 nm, and 2.07 × 1013 Jones at 1540 nm, respectively, which is much better than that of previously reported narrowband NIRPDs. Our work has opened up new avenues for developing next-generation narrowband NIRPDs.