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Analysis of the charge transfer and separation in electrically doped organic semiconductors by electron spin resonance spectroscopy
摘要： We investigated the charge generation mechanism of electrically doped organic semiconductors (OSs) by electron spin resonance (ESR) analysis. ESR spectroscopy was used to successfully evaluate the radical density of p-doped OSs to estimate the charge transfer efficiency (CTE) of various doped systems. The results showed that the CTE is efficient close to 100% if the dopant molecules are homogenously dispersed and the energy difference (?E) between the highest occupied molecular orbital (HOMO) level of the host molecule and lowest unoccupied molecular orbital (LUMO) level of the p-dopant is large. The charge separation efficiency to form free carriers from the radicals is rather low (less than 12% in this study) and is a dominant factor controlling the charge generation efficiency (CGE). An organic dopant molybdenum tris[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene] turns out to be an efficient dopant with the CGE of 9.7% due to high CTE originating from homogenous dispersion of the organic p-dopants and low LUMO level, i.e., large ?E.
关键词： charge generation efficiency,p-dopant,charge transfer,electron spin resonance spectroscopy,Organic semiconductors,charge separation
更新于2025-09-19 17:15:36
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Continuous and Ultrafast Preparation of In(OH) <sub/>3</sub> , InOOH, and In <sub/>2</sub> O <sub/>3</sub> Series in a Microreactor for Gas Sensors
摘要： In(OH)3 and InOOH were synthesized in a high-temperature continuous flow microreactor, which was much faster than the hydrothermal synthesis in the Teflon-lined autoclave. The phase transition interval of In(OH)3 and InOOH is measured and the effect of aging temperatures on equilibrium compositions was also theoretically calculated. A transformation from nanorods to nanocubes was observed when the aging temperatures increased. In(OH)3 and InOOH were also synthesized with Sn dopant, which was proved to be beneficial for the transformation from In(OH)3 to InOOH. The sensors based on cubic and hexagonal In2O3 particles showed a fast response (4~5 s) and recovery (12~15 s) speed to acetone vapor at the optimum operating temperature of 290 oC. The sensor based on hexagonal In2O3 showed a higher response than that based on cubic In2O3. This work provided a rapid, continuous and high-temperature synthesis method of an In(OH)3, InOOH and In2O3 series.
关键词： Indium hydroxide (In(OH)3),Tin dopant,Indium oxide(In2O3),Indium oxyhydroxide (InOOH),Gas sensors
更新于2025-09-19 17:15:36
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Dopant-free X-shaped D-A type hole-transporting materials for p-i-n perovskite solar cells
摘要： Azomethine compounds are accessible for palladium-free routes, paving a way for developing highly efficient and eco-friendly hole-transporting materials. This study reports three organic dopant-free X-shaped molecules (named D31, D32, and D33) were systematically designed, synthesized and characterized for fabricating p-i-n perovskite solar cells. The X-shaped design is based on a benzene core unit with four arms attached. Two of them are triphenylamines and two are azomethine bridges connected to functionalized phenyl rings (-H, -OCH3, -CN). These materials show suitable energy levels with respect to that of CH3NH3PbI3 perovskite. Based on this design, it is found that the hydrophobic nature of the three new compounds not only favors the formation of large grained and dense perovskite films but also improves stability of the devices. More encouragingly, the cyano-substituted D33 with donor-acceptor (D-A) type structure exhibit the superiority of high hole mobility and good film-forming property. The optimized unencapsulated device based on D33 in ambient environment exhibit 17.85% efficiency and retained 70% of the initial PCE after 400 hours.
关键词： perovskite solar cells,azomethine,dopant-free,hole-transport materials,donor-acceptor
更新于2025-09-19 17:13:59
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Efficient blue organic light-emitting diodes with low operation voltage by improving the injection and transport of holes
摘要： In this work, we reported the highly efficient organic electroluminescent (EL) devices based on blue phosphorescent material FIr6. By utilizing p-type dopant HAT-CN as hole injection layer material, the injection of holes from the anode was significantly improved. In addition, doping HAT-CN into hole transport layer (HTL) and inserting thin TcTa film between HTL and light-emitting layer (EML) improved the transport of holes. The stepwise energy levels between functional layers reduced the injection barriers of carriers, thus improving the balance of carriers within EML. Finally, highly efficient blue EL device realized the maximum current efficiency, power efficiency, external quantum efficiency (EQE) and brightness up to 39.14 cd/A, 38.68 lm/W, 24.6% and 17201 cd/m2, respectively. Even at the high brightness of 1000 cd/m2 (3.7 V), current efficiency and EQE as high as 36.73 cd/A and 23.1%, respectively, can still be retained by the same device. Our investigation provides an idea for the design of high-performance devices with low operation voltage and slow efficiency roll-off.
关键词： Electroluminescence,Operation voltage,Efficiency roll-off,p-type dopant
更新于2025-09-19 17:13:59
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A Dopant‐Free Polymeric Hole‐Transporting Material Enabled High Fill Factor Over 81% for Highly Efficient Perovskite Solar Cells
摘要： Although perovskite solar cells (PVSCs) have achieved rapid progress in the past few years, most of the high-performance device results are based on the doped small molecule hole-transporting material (HTM), spiro-OMeTAD, which affects their long-term stability. In addition, some defects from under-coordinated Pb atoms on the surface of perovskite films can also result in nonradiative recombination to affect device performance. To alleviate these problems, a dopant-free HTM based on a donor-acceptor polymer, PBT1-C, synthesized from the copolymerization between the benzodithiophene and 1,3-bis(4-(2-ethylhexyl)thiophen-2-yl)-5,7-bis(2-alkyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione units is introduced. PBT1-C not only possesses excellent hole mobility, but is also able to passivate the surface traps of the perovskite films. The derived PVSC shows a high power conversion efficiency of 19.06% with a very high fill factor of 81.22%, which is the highest reported for dopant-free polymeric HTMs. The results from photoluminescence and trap density of states measurements validate that PBT1-C can effectively passivate both surface and grain boundary traps of the perovskite.
关键词： passivation,polymers,dopant-free,perovskite solar cells
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - In Situ Transmission Electron Microscopy: A Powerful Tool for the Characterization of Carrier-Selective Contacts
摘要： This paper investigates the manufacturability-aware process of p-n junction formation for photovoltaic cells involving with Si nanoparticle layer. The furnace-based dopant diffusion process of forming a p-n junction consumes a substantial amount of energy. In addition, repetitive production steps prevent the possibility of Si ink-based cells integrating onto flexible substrates. This research examined the local heating dopant diffusion process by using a fiber laser at a wavelength of 1064 nm. The infrared beam is delivered onto the wafer stack with a nanoparticle carbon layer and n-type Si ink layer on p-type Si substrates. The nanoparticle carbon film absorbs infrared beam energy and converts photon energy as a thermal source to diffuse the n-type dopant in Si ink into the p-type Si wafer. The Si ink in this paper contains a mixture of Si nanoparticles and an n-type spin-on dopant solution. The TEM results show that Si nanoparticles are uniformly dispersed on the Si wafer surface. This research investigated sheet resistance as a function of laser parameters, including laser power, scanning speed, and pulse frequency for the samples coated with Si ink. Secondary ion mass spectroscopy measurements indicate the presence of an n-type dopant in p-type substrates, with an approximate diffusion depth of 100 nm. The results indicate that the proposed infrared laser treatment technique is promising for the formation of p-n junctions with Si ink-based photovoltaic cells.
关键词： Flexible photovoltaic cell,fiber laser,pn junction,spin-on dopant (SOD),silicon ink,carbon nanoparticle,silicon nanoparticle
更新于2025-09-19 17:13:59
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Dopant‐Free Hole Transporting Molecules for Highly Efficient Perovskite Photovoltaic with Strong Interfacial Interaction
摘要： One of the attractive ways to develop efficient and cost-effective inverted perovskite solar cells (PVSCs) is through the use of dopant-free hole transporting materials (HTMs) with facile synthesis and a lower price tag. Herein, two organic small molecules with a fluorene core are presented as dopant-free HTMs in inverted PVSCs, namely, FB-OMeTPA and FT-OMeTPA. The two molecules are designed in such a way they differ by replacing one of the benzene rings (FB-OMeTPA) with thiophene (FT-OMeTPA), which leads to a significantly improved coplanarity as manifested in the redshift of the absorbance and a smaller bandgap energy. Density functional theory calculations show that FT-OMeTPA has a strong Pb2+–S interaction at the FT-OMeTPA/perovskite interface, allowing surface passivation and facilitating charge transfer across interfaces. As a result, the PVSCs based on FT-OMeTPA exhibit a much higher hole mobility, power conversion efficiency, operational stability, and less hysteresis as compared with devices based on FB-OMeTPA.
关键词： hole transporting materials,dopant-free,p-i-n,inverted perovskite photovoltaics,interfacial interactions
更新于2025-09-19 17:13:59
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Manganese‐doped green tea‐derived carbon quantum dots as a targeted dual imaging and photodynamic therapy platform
摘要： In this work, manganese-doped carbon quantum dots (Mn-CQDs) have been synthesized through a one-pot hydrothermal method by using waste green tea. The Mn2+ dopants were introduced to impart magnetic resonance capability. Upon optimization of the experimental conditions, magnetofluorescent Mn-CQDs exhibit an excitation-dependent blue emission. The abundant functional groups on Mn-CQDs not only promote water solubility but also allow straightforward functionalization with amine groups. The amine-terminated Mn-CQDs were then subsequently conjugated to folic acid (FA) and chlorin e6 (Ce6) to obtain the Mn-CQDs@FA/Ce6 magnetofluorescent photodynamic therapy (PDT) agent. in vitro studies using three different cells indicated specific targeting of Mn-CQDs@FA/Ce6 to the overexpressing folate receptor human epithelial carcinoma cell line (HeLa) cancer cells. Furthermore, Mn-CQDs@FA/Ce6 enhanced magnetic resonance imaging (MRI) signal with an r2/r1 ratio of 5.77. Favorably, by using the Mn-CQDs@FA delivery system, active Ce6 can reach the cellular interior while its red fluorescence (FL) and reactive oxygen species generation can be retained, as has been verified by confocal microscopy. in vitro cell viability studies verified the biocompatibility of Mn-CQDs@FA/Ce6 nanohybrid with no significant toxicity up to 500 ppm while PDT treatment with 5 min irradiation (671 nm, 1 W cm?2) was effective in killing >90% of cells. The light-triggered Mn-CQDs@FA/Ce6 multifunctional hybrid can serve as a dual-modal FL/MRI probe and as an efficient PDT agent to detect and eradicate cancer cells remotely.
关键词： Mn dopant,photoluminescence,carbon quantum dots,photodynamic therapy,MRI
更新于2025-09-19 17:13:59
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N-type doping of Ge by P spin on dopant and pulsed laser melting
摘要： N-type doping of Ge based on spin on dopant sources and pulsed laser melting has been proposed as an alternative to the use of complex and expensive techniques such as ion-implantation or molecular beam epitaxy. Optimization of the n+/p junction has been carried out with a KrF laser (of 22 ns pulse duration) by studying the effect of different laser fluences and the number of pulses. The diffusion profiles, sheet resistance, carrier density and mobility have been determined by secondary ion mass spectrometry and Van der Pauw–Hall measurements. By properly selecting the range of laser energy density and number of pulses, a high level of activation (>1019 cm?3) with good mobility (350–450 cm2 V?1 s?1) and low sheet resistance (<50 Ω/,) has been achieved. In addition, the good crystalline quality of the samples has been confirmed by high-resolution x-ray diffraction measurements, demonstrating the viability of such a low-cost manufacturing process for next generation Ge-based devices.
关键词： germanium,spin on dopant,phosphorus doping,semiconductors,pulsed laser melting
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Electron-Conductive, Hole-Blocking Contact for Silicon Solar Cells
摘要： This paper presents a simple mathematical expression to model the effect of statistical dopant fluctuations on threshold voltage (Vth) of junction field-effect transistors (JFETs). The random discrete doping (RDD) in the active device area is used to derive an analytical model to compute the standard deviation, σ Vth,RDD of the Vth-distribution for any arbitrary channel doping profiles. The model shows that the Vth-variability in JFETs depends on the active device area, channel doping concentration, and the depth of the channel depletion region of the gate/channel pn-junction. The model is applied to compute σ Vth,RDD for symmetric and asymmetric source/drain double-gate n-channel JFETs. The simulation results show that the model can be used for predicting Vth-variability in JFETs.
关键词： modeling threshold voltage variability,random discrete doping,process variability in JFETs,statistical dopant fluctuations,JFET threshold voltage variability,Junction field-effect transistor (JFET)
更新于2025-09-19 17:13:59