Passivating {100} Facets of PbS Colloidal Quantum Dots via Perovskite Bridges for Sensitive and Stable Infrared Photodiodes

Abstract

Solution‐processed PbS colloidal quantum dots (CQDs) are promising optoelectronic materials for next‐generation infrared imagers due to their monolithic integratability with silicon readout circuit and tunable bandgap controlled by CQDs size. However, large‐size PbS CQDs (diameter >4 nm) for longer shortwave‐infrared photodetection consist mainly of {100} facets with incomplete surface passivation and unsatisfied stability. Here, it is reported that perovskite‐bridged PbS CQDs, in which the {100} facets of the CQDs are epitaxially bridged with CsPbI3–xBrx perovskite, can achieve improved passivation and enhanced stability in comparison with the traditional strategies. The resultant infrared CQDs photodiodes exhibit significantly reduced dark current, nearly 50% enhanced photoresponse, and improved work stability. These superior properties synergistically produce the most balanced performance (with a high −3 dB bandwidth of 42 kHz and an impressive specific detectivity of 6.2 × 1012 Jones) among the reported CQDs photodetectors.

High-Performance Colloidal Quantum Dot Photodiodes via Suppressing Interface Defects

“…This value is advanced compared with the previously reported short-wavelength infrared PbS CQDs photodetectors (Figure S11). ,,− …”

Transient Measurements and Simulations Correlate Exchange Ligand Concentration and Trap States in Colloidal Quantum Dot Photodetectors

“…Additionally, EQE is another photodetector performance parameter directly affected by trap state density. − A highest EQE of 68.5% was achieved with the 140 mM ligand exchange (Figure D). Decreasing the ligand concentration decreased the EQE.…”

Epitaxial 2D PbS Nanosheet‐Formamidinium Lead Triiodide Heterostructure Enabling High‐Performance Perovskite Solar Cells

“…[21][22][23][24] Compared with other materials, the Pb-Pb distance and the crystal structure of cubic PbS with the rock-salt structure are close to those of organic-inorganic perovskites, and it has been observed that MAPbI 3 , CsPbBr x I 3−x , and Cs 0.05 (MA 0.17 FA 0.83 ) 0.95 Pb(I 0.9 Br 0.1 ) 3 perovskites can epitaxially grow on PbS nanocrystals. [ [25][26][27][28][29][30] Notably, epitaxial growth is one of the keys to obtaining high-quality heterostructures with low defect density and is the premise to utilize surface chemistry on regulating the properties of heterostructures. For improving the stability of FAPbI 3 perovskites, Mora-Seró's group reported that the (100) plane of PbS quantum dots tended to bind with 𝛼-FAPbI 3 and this chemical bonding could decrease the energy of 𝛼-FAPbI 3 at room temperature thus showing better stability.…”