Reconstructing Quantum Dot Surfaces via Dual-Functional Ligand Pairing Enables Efficient Shortwave Infrared Optoelectronics

초록

The growing demand for efficient infrared photon harvesting has spotlighted colloidal quantum dots (CQDs) as versatile, solution-processable absorbers for emerging optoelectronics, including photovoltaics (PVs), thermophotovoltaics (TPVs), and photodetectors (PDs). However, achieving narrow size distribution and complete surface passivation remains particularly challenging for shortwave infrared (SWIR) CQDs, limiting their potential in infrared optoelectronics. Here, we demonstrate a SWIR-suited ligand-pairing strategy to precisely tailor CQD surfaces during the synthesis and ligand-exchange processes. A reactivity-controlled thiourea-based precursor results in improved size uniformity and colloidal stability, even for large CQDs. The resultant CQD surfaces are further reconstructed by dual-functional HBr ligands that effectively remove native amine ligands and passivate (100) facets, simultaneously. As a result, the fabricated SWIR CQD optoelectronics exhibit 94.5% internal quantum efficiency, achieving notable performance across three key SWIR applications (PV, TPV, PD), thereby setting a new benchmark for solution-processed SWIR optoelectronics.

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