Haodong Tang

Defect-mediated leakage at charge-selective contacts fundamentally limits the performance of colloidal quantum dot (QD) short-wave infrared (SWIR) photodiodes. Here, we address this challenge by inserting a thin conjugated polymer (PM6) interlayer between the PbS-EDT hole transport layer and the MoOx electrode. This interlayer suppresses interfacial trap-assisted transport, reduces leakage pathways, and stabilizes charge dynamics, thereby achieving a more regulated interfacial transport regime. Consequently, the PM6-modified devices exhibit a markedly reduced dark current density of 70.1 nA/cm2 at −0.5 V, a high external quantum efficiency of 82.56% (zero bias) at 1300 nm, and a significantly suppressed noise spectral density, leading to an enhanced specific detectivity of 2.62 × 1011 Jones. Our findings establish polymer interlayer engineering as a simple and scalable approach to realize low-noise, high-stability SWIR photodetectors.

Hole transport layers (HTLs) in colloidal quantum dot (QD) solar cells are conventionally prepared through multi-step ligand exchange processes, which often induce surface damage and trap-state defects. To address these limitations, this work presents an inorganic–organic in situ synergistic passivation strategy for the one-step synthesis of a stable dual-ligand p-type PbS QD conductive ink. Employing lead thiocyanate (Pb(SCN)2) as the precursor together with 2-furanmethanethiol (FMT) as the synergistic ligand enables the formation of a dual-ligand co-adsorption network. The resulting PbS QD conductive ink forms a p-type conducting interfacial layer with favorable cascade energy-level alignment and reduces the trap-state density (tDOS) by approximately 38%. Utilizing this directly synthesized p-type PbS QD conductive ink as the HTL, the resulting solar cells achieve a champion power conversion efficiency (PCE) of 13.60%, enabled by prolonged carrier lifetimes and accelerated charge extraction kinetics. This work establishes a practical chemical design strategy for engineering PbS QD interfaces and simplifying HTL fabrication.

Colloidal lead sulfide quantum dots are attractive for short‐wave infrared photodetectors due to their tunable bandgap and solution‐process compatibility, yet device performance is often limited by high dark current, inefficient carrier extraction, and poor stability. Here, we report a new strategy of combining thermal spin‐coating and annealing that improves quantum dot film quality by regulating solvent evaporation kinetics and stacking behavior during deposition. Elevating the substrate temperature during spin‐coating induces dense and uniform quantum dot assemblies with reduced trap density and improved interfacial contact. Photodetectors fabricated at an optimized temperature of 65°C exhibit substantially enhanced performance, including a responsivity of 0.765 A/W, a specific detectivity of 3.57 × 10 ^{1 1} Jones, and a −3 dB bandwidth of 108 kHz, accompanied by over 50% reduction in dark current density. Importantly, the optimized devices show improved long‐term stability, retaining lower dark current and higher external quantum efficiency after prolonged storage without encapsulation. Leveraging these advantages, the photodetectors are further integrated into an imaging array and applied to non‐invasive glucose monitoring using dual‐wavelength ratiometric detection. This work establishes thermal spin‐coating as a simple and scalable route toward high‐performance, stable quantum dot infrared photodetectors for imaging and biomedical sensing applications.

The electrochemical performance of Ti ₃ C ₂ T _x MXene arises from chemical and electrostatic interactions between its surface terminations and interlayer molecules. Moving beyond the conventional paradigm of relying on the intercalation of external guest species to modulate this network, this study addresses a more fundamental question: can the interaction environment be intrinsically engineered from within the MXene lattice? Here, carbon (C) vacancies are introduced as a precise strategy to polarize the surface electronic structure, specifically enhancing the electronegativity of oxygen terminations. This polarization strengthens the hydrogen bonding (H‐bonding) interactions with confined water, leading to the formation of a thermally stable, “active and fixed” interlayer architecture. This optimized structure results in a significant increase in intrinsic capacitance, with the Ti ₃ C _1.7 electrode achieving 348 F g ⁻¹ at 5 mV s ⁻¹ , a 47% enhancement over the near‐stoichiometric Ti ₃ C _2.0 . Subsequent anodic oxidation alleviated ion diffusion limitations at high rates, synergistically improving rate capability. The co‐engineered electrode achieved a high capacitance of 382 F g ⁻¹ while retaining 45% capacitance at an ultra‐high scan rate of 5000 mV s ⁻¹ . This work establishes the rational design of interfacial H‐bonding networks as a core principle for advanced MXene electrodes, offering a pathway to high energy and power densities.

Chirality‐dependent optoelectronics and biological interactions have both attracted significant attention over the past several decades. However, interdisciplinary synergy between these two fields remains limited, largely due to the lack of theoretical support and practical demonstrations. Herein, we report the fabrication of biomolecule‐tailored chiral PbS films via a solid‐state ligand exchange method, enabling the achievement of a maximum chiroptical anisotropic factor ( g ‐factor) of 2.36 × 10 ⁻³ . These chiral PbS films were integrated into circularly polarized short‐wave infrared (CP‐SWIR) photodetectors, exhibiting a high responsivity beyond 0.3 A/W and a detectivity beyond 8.6 × 10 ¹¹ Jones under the irradiation (L‐PbS film under left‐handed CP‐SWIR). More importantly, such chirality‐mediated phenomenon enables antibacterial activity through a photo‐microcurrent generation effect. It eventually provides a significant 39% difference in E. coli mortality rate when the L‐PbS‐based photosensitive device is subject to homochiral versus heterochiral CP‐SWIR illumination. This strategy offers a robust platform for cross‐collaborations between chiroptical optoelectronic devices and chirality‐related biological issues.

Halide‐capped PbS colloidal quantum dots (CQDs) prepared via solution‐phase ligand exchange (SPLE) are promising materials for next‐generation optoelectronic devices owing to their effective surface passivation. Nevertheless, deep traps and band‐tail states in CQD solids are often intertwined, obscuring individual impacts on device performance. Here, we introduce two alkylamines, pentylamine (PA) and hexylamine (HA), as additives in a butylamine‐based cosolvent system to decouple these electronic defects. The HA additive significantly suppresses deep trap states by improving halide passivation and directly coordinating with Pb on the CQD surface, whereas the PA additive promotes structural ordering and thus reduces band‐tail states in CQD solids due to the formation of a 2D layered structure through its preferential interactions with the halide matrix. Incorporating the HA additive enables PbS CQD photodetectors (PDs) in zero‐bias photovoltaic mode to achieve a remarkable responsivity of 0.76 A/W and an external quantum efficiency of 72% in the short‐wave infrared (SWIR) region. Thus, device performance is dominated by deep traps at the CQD surface and interfacial defects in the device architecture, providing insights for high‐performance CQD optoelectronic devices.

1-Octanethiol (OT)-modified PbS quantum dots (QDs) exhibit enhanced monodispersity, reduced defects, and octahedral-like morphologies, enabling high-performance SWIR photodetectors with high EQE and specific detectivity.