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Oxygen Plasma-Induced p-type Doping Improves Performance and Stability of PbS Quantum Dot Solar Cells
摘要： PbS quantum dots (QDs) have been extensively studied for photovoltaic applications thanks to their facile and low-cost fabrication processing and interesting physical properties such as size-dependent and tunable bandgap. However, the performance of PbS QDs based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer (HTL) can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report on a low-power oxygen plasma treatment as a rapid and cost-effective method to effectively recover the device performance and stability. Our optimization results show that a 10 min treatment is the best condition, resulting in an enhanced power conversion efficiency (PCE) from 6.9% for the as-prepared device to 9% for the plasma treated one. Moreover, our modified device shows long-term shelf-life stability.
关键词： colloidal quantum dots,plasma,lead sulfide,photovoltaics,stability
更新于2025-10-22 19:40:53
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Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals
摘要： Intraband and plasmonic transitions have appeared over the last years as an interesting tool to achieve optical absorption in the mid infrared. Tuning the doping magnitude has become a major challenge not only to tune the optical spectrum but also properties such as the dark current or the time response. Here we investigate the case of self-doped HgSe colloidal quantum dots (CQDs). Tuning of the doping was so far relying on band bending induced by a dipole design at the nanoparticle surface. With such a surface gating approach, it is difficult to conciliate both the massive tuning of the Fermi level with the preservation of transport properties of the CQD arrays. Here we propose a strategy to graft functionalized polyoxometalates (POMs) at the CQD surface and obtain simultaneously a massive tuning of the carrier density (≈5 electrons per nanoparticle) and conduction properties. We bring a consistent demonstration of the HgSe CQD doping decrease by a charge transfer to the POM. This method is highly promising for large tuning of carrier density in degenerately doped semiconductor nanoparticles.
关键词： Intraband,mid infrared,charge transfer,polyoxometalates,plasmonic transitions,doping control,HgSe colloidal quantum dots
更新于2025-09-23 15:21:21
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[IEEE 2018 23rd Opto-Electronics and Communications Conference (OECC) - Jeju Island, Korea (South) (2018.7.2-2018.7.6)] 2018 23rd Opto-Electronics and Communications Conference (OECC) - 2.8?μm infrared photodetectors based on PbSe colloidal quantum dot films
摘要： In this study, we synthesized monodisperse and high purity PbSe CQDs and then demonstrated the photodetectors working at different wavelengths up to 2.8 μm. Colloidal quantum dots (CQDs) have been studied extensively due to their attractive optoelectronic properties such as high luminescence efficiency, large dipole moment, strong light absorption, good photo-stability, and multiple electron hole pair generation. More importantly, the strong quantum confinement effect allows us to tailor the energy band gap of these materials by controlling their size in a cost-effective wet chemical synthesis. These advantages bring CdSe-based CQDs to a competitive market of lighting and display technology today. The research on lead based chalcogenide (PbTe, PbS, and PbSe) CQDs for infrared applications has also received much scientific and technological attention because of the possibility to tune the bandgap in the infrared wavelength range. Among lead based chalcogenide family, lead selenide (PbSe) CQDs have received more attention in not only photodetectors but also many infrared optoelectronic applications like solar cells, light emitting diodes, etc [1-4]. In the present work, we report about high performance photodetectors at a broad spectral range, for the first time, up to 2.8 μm based on our high quality, monodisperse PbSe CQDs. We deposited thin films of synthesized PbSe CQDs on the patterned interdigitated platinum electrodes by a drop casting method to create photodetectors. These photodetectors with different thicknesses of the PbSe CQD film were studied and optimized in detail for the best performance. The photocurrent responses were recorded as a function of bias voltage using infrared LED illuminations with wavelengths of up to 2.8 μm.
关键词： infrared photodetectors,detectivity,responsivity,PbSe colloidal quantum dots,photocurrent
更新于2025-09-23 15:21:01
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Colloidal Quantum-Dots/Graphene/Silicon Dual-Channel Detection of Visible Light and Short-Wave Infrared
摘要： Integration of infrared detectors with current silicon-based imagers would not only extend their spectral sensing range but also enables numerous applications including thermal imaging, machine vision, and spectrometers. Here, we report the development of a dual-channel photodetector by depositing a colloidal quantum dot (CQDs) infrared photodiode onto a graphene/p-Silicon Schottky diode to provide simultaneous visible and infrared photoresponse channels. The HgTe photodiode is patterned into a semitransparent mesh-structure so that the visible light reaches the Silicon substrate with varying fill factors. The graphene/silicon Schottky junction has a responsivity of ~0.9 A/W in the visible and the infrared CQDs photodiode has a detectivity of ~5×109 Jones at 2.4μm, for a filling factor of 0.1.
关键词： Photodetectors,Graphene/silicon Schottky junction,Visible/infrared,Colloidal quantum dots
更新于2025-09-23 15:21:01
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Mid-Wavelength Infrared Responsivity of Colloidal Quantum Dot/Organic Hybrid Photodetectors
摘要： Colloidal quantum dot/organic hybrid materials approach offer a path toward engineering solution-processed photodetectors with extended spectral responsivity in the infrared. We demonstrate this approach in the technologically important thermal infrared region of mid-wavelength infrared, utilizing a solution blend of Ag2Se colloidal quantum dots and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We report on the device fabrication and their room temperature optical, electrical, and optoelectronic properties. At room temperature, a responsivity of 0.2 mA/W was measured under 5 μm irradiation and 5 V bias. The new hybrid optoelectronic film demonstrated the advantage of cost-effectiveness and greater fabrication versatility than the single crystal or epitaxial semiconductors that comprise today’s infrared technologies.
关键词： Colloidal quantum dots,Photodetectors,Mid-wavelength infrared,Organic hybrid,Responsivity
更新于2025-09-23 15:21:01
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On-demand tuning of charge accumulation and carrier mobility in quantum dot solids for electron transport and energy storage devices
摘要： Assemblies of colloidal quantum dots (CQDs) are attractive for a broad range of applications because of the ability to exploit the quantum con?nement effect and the large surface-to-volume ratio due to their small dimensions. Each application requires different types of assemblies based on which properties are intended to be utilized. Greater control of assembly formation and optimization of the related carrier transport characteristics are vital to advance the utilization of these materials. Here, we demonstrate on-demand control of the assembly morphology and electrical properties of highly crosslinked CQD solids through the augmentation of various assembly methods. Employment of electric-double-layer (EDL) gating on these assembly structures (i.e., an amorphous assembly, a hierarchical porous assembly, and a compact superlattice assembly) reveals their intrinsic carrier transport and accumulation characteristics. Demonstrations of high electron mobility with a high current modulation ratio reaching 105 in compact QD ?lms and of a record-high areal capacitance of 400 μF/cm2 in an electric-double-layer supercapacitor with very thin (<100 nm) QD hierarchical porous assemblies signify the versatility of CQDs as building blocks for various modern electronic devices.
关键词： electron transport,electric-double-layer gating,energy storage devices,carrier mobility,colloidal quantum dots
更新于2025-09-23 15:21:01
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Influence of photoactivation on luminescent properties of colloidal InP@ZnS quantum dots
摘要： The use of photo- and thermoactivation during the liquid-phase synthesis of colloidal quantum dots was found to yield luminescing InP@ZnS quantum dots with a luminescence quantum yield close to unity. Activation mode was found to have little or no influence on the maximal luminescent efficiency but affect particle size distribution. Compared to thermal activation, photoactivation ensures the formation of more monodispersed particles.
关键词： Colloidal quantum dots,Thermoactivation,Indium phosphide,Luminescence quantum yield,Photoactivation
更新于2025-09-23 15:19:57
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Dual-Wavelength Lasing in Quantum-Dot Plasmonic Lattice Lasers
摘要： Arrays of metallic particles patterned on a substrate have emerged as a promising design for on-chip plasmonic lasers. In past examples of such devices, the periodic particles provided feedback at a single resonance wavelength, and organic dye molecules were used as the gain material. Here, we introduce a flexible template-based fabrication method that allows a broader design space for Ag particle-array lasers. Instead of dye molecules, we integrate colloidal quantum dots (QDs), which offer better photostability and wavelength tunability. Our fabrication approach also allows us to easily adjust the refractive index of the substrate and the QD-film thickness. Exploiting these capabilities, we demonstrate not only single-wavelength lasing but dual-wavelength lasing via two distinct strategies. First, by using particle arrays with rectangular lattice symmetries, we obtain feedback from two orthogonal directions. The two output wavelengths from this laser can be selected individually using a linear polarizer. Second, by adjusting the QD-film thickness, we use higher-order transverse waveguide modes in the QD film to obtain dual-wavelength lasing at normal and off-normal angles from a symmetric square array. We thus show that our approach offers various design possibilities to tune the laser output.
关键词： surface lattice resonances,dual-wavelength laser,colloidal quantum dots,plasmonics,nanolaser,template stripping,polarization
更新于2025-09-23 15:19:57
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[Institution of Engineering and Technology 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Lecce, Italy (23-25 May 2018)] 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Colloidal quantum dots for optoelectronic applications: fundamentals and recent progress
摘要： In this work, we present highlights and major milestones in the field of CQDs, starting from their optical and electronic properties that can be tailored not only by the atomic composition but also by the size, shape, and surface functionalization. We will also touch on CQD synthesis, processing and assembly, emphasizing their flexibility, low cost, low temperature and scalability. We will review recent advances in the design and fabrication of optoelectronic devices based on colloidal semiconductor quantum dots, with emphasis on light emitters, detectors and solar cells. We conclude with a short discussion on the large potentialities of this new class of materials as well as the challenges that must be addressed towards solution-processed functional optoelectronic nanomaterials for their practical applications in various fields.
关键词： semiconductor nanostructures,optoelectronic devices,colloidal quantum dots
更新于2025-09-23 15:19:57
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Electrochemically-stable ligands bridge the photoluminescence-electroluminescence gap of quantum dots
摘要： Colloidal quantum dots are promising emitters for quantum-dot-based light-emitting-diodes. Though quantum dots have been synthesized with ef?cient, stable, and high colour-purity photoluminescence, inheriting their superior luminescent properties in light-emitting-diodes remains challenging. This is commonly attributed to unbalanced charge injection and/or interfacial exciton quenching in the devices. Here, a general but previously overlooked degradation channel i.e., operando electrochemical reactions of surface ligands with injected charge carriers, is identi?ed. We develop a strategy of applying electrochemically-inert ligands to quantum dots with excellent luminescent properties to bridge their photoluminescence-electroluminescence gap. This material-design principle is general for boosting electroluminescence ef?ciency and lifetime of the light-emitting-diodes, resulting in record-long operational lifetimes for both red-emitting light-emitting-diodes (T95 > 3800 h at 1000 cd m?2) and blue-emitting light-emitting-diodes (T50 > 10,000 h at 100 cd m?2). Our study provides a critical guideline for the quantum dots to be used in optoelectronic and electronic devices.
关键词： electroluminescence,light-emitting-diodes,photoluminescence,Colloidal quantum dots,electrochemical stability
更新于2025-09-23 15:19:57