Spray Coated Colloidal Quantum Dot Films for Broadband Photodetectors

Abstract

A technique for scalable spray coating of colloidal CdSeTe quantum dots (QDs) for photovoltaics and photodetector applications is presented. A mixture solvent with water and ethanol was introduced to enhance the adhesive force between QDs and the substrate interface. The performance of the detector reached the highest values with 40 spray coating cycles of QD deposition. The photodetectors without bias voltage showed broadband response in the wavelength range of 300–800 nm, and high responsivity of 15 mA/W, detectivity of more than 1011 Jones and rise time of 0.04 s. A large size QD-logo pattern film (10 × 10 cm2) prepared by the spray coating process displayed excellent uniformity of thickness and absorbance. The large area detectors (the active area 1 cm2) showed almost the same performance as the typical laboratory-size ones (the active area 0.1 cm2). Our study demonstrates that the spray coating is a very promising film fabrication technology for the industrial-scale production of optoelectronic devices.

Near-infrared imager based on high performance organic photodetector using a-IGZO as electron transport layer

“…Since the resolution is limited by CMOS architecture rather than by photodiode integration process, there is potential to catch up with CMOS sensor in terms of pixel pitch (TFIS, state-of-the-art 0.90 μm 7 ) in the near future. Thinfilm technology offers large area, low temperature deposition of thin-film absorber materials using different simple solution processing techniques such as spin coating, spray pyrolysis, and printing 8,9,[11][12][13] . The transport layers and the top contact can also be deposited by solution process or thermal evaporation or sputtering.…”

“…Maximum NIR EQE of ~57% at 910 nm and ~32% at 940 nm are evident from Figure 3b. The high EQE in the NIR region and low dark current density of the OPD result in a high responsivity of 0.41 AW -1 and >10 13 Jones of shot-noise limited specific detectivity (D*) at 900-920 nm range. Carefully designed and optimized inorganic oxide semiconductors MoOx and a-IGZO as HTL and ETL with high mobilities (in contrast to organic transport layers) result in a fast transient photo response speed of 0.663/1.49 (rise/fall) μs.…”

Accelerating colloidal quantum dot innovation with algorithms and automation

“…Before application to devices, QDs must be processed post-synthesis—this can involve separation, purification and application of QDs to the target material. Currently, QDs are typically washed and purified separate from the reactor system and then applied to devices via variety of different methodologies including spin-coating, 122 inkjet printing, 123 spray coating, 124 and blade coating, 125 as typical examples. Bridging this gap between synthesis and application, current research is exploring how altering the structural properties of QDs affect the stability and efficacy when applied, to ensure developments in production methods can meet industry requirements.…”

Colossal Vacancy Effect of 2D CuInP2S6 Quantum Dots for Enhanced Broadband Photodetection

“…21,22 Meanwhile, the high solubility of 2D QDs enables large-scale straightforward compact integration on various substrates (rigid, curved, or flexible) with the help of drop-casting, 23 spin-coating, 24 and spraying or inkjet printing. 25,26 However, the excellent optoelectronic performances of most reported 2D QD-based photodetectors, e.g., high responsivity and wide response range, are achieved by applying gate voltage or forming a heterostructure with other materials (2D materials, Si, GaAs), 24,27−32 which complicates the fabrication process and increases costs, further limiting the practical application of 2D QDs. In fact, owing to the strong recombination and scattering of charges resulting from interfacial trap/defect density, 33 the intrinsic optoelectronic performances of single 2D QD materials without heterostructures, external modulations, and vacuum test conditions are quite poor, e.g., the weak responsivities of 2 × 10 −3 and 1.33 × 10 −1 A/W in graphene and MoS 2 QDs, respectively.…”

“…These methods have been widely applied in various applications, including photodetectors, − photocatalysis, batteries, supercapacitors, and water electrolysis. , Two-dimensional materials can be additionally confined in the lateral dimensions to form 2D quantum dots (2D QDs), which is an effective way to tune the band structures of 2D parent materials to further realize numerous unique properties . For instance, compared with graphite, graphene QDs exhibit widely tunable photoluminescence, side- and shape-controlled optical characteristics, higher integration density, nontoxicity as well as higher stability. , Meanwhile, the high solubility of 2D QDs enables large-scale straightforward compact integration on various substrates (rigid, curved, or flexible) with the help of drop-casting, spin-coating, and spraying or inkjet printing. , However, the excellent optoelectronic performances of most reported 2D QD-based photodetectors, e.g., high responsivity and wide response range, are achieved by applying gate voltage or forming a heterostructure with other materials (2D materials, Si, GaAs), ,− which complicates the fabrication process and increases costs, further limiting the practical application of 2D QDs. In fact, owing to the strong recombination and scattering of charges resulting from interfacial trap/defect density, the intrinsic optoelectronic performances of single 2D QD materials without heterostructures, external modulations, and vacuum test conditions are quite poor, e.g., the weak responsivities of 2 × 10 –3 and 1.33 × 10 –1 A/W in graphene and MoS 2 QDs, respectively. , Consequently, developing 2D QD materials for superior intrinsic optoelectronic performance without gate voltage, heterostructure, and vacuum is critical to meet the growing demand for high-performance electronic and optoelectronic devices.…”