- 标题
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Effects of hole-boring and relativistic transparency on particle acceleration in overdense plasma irradiated by short multi-PW laser pulses
摘要： Propagation of short and ultraintense laser pulses in a semi-infinite space of overdense hydrogen plasma is analyzed via fully relativistic, real geometry particle-in-cell (PIC) simulations including radiation friction. The relativistic transparency and hole-boring regimes are found to be sensitive to the transverse plasma field, backward light reflection, and laser pulse filamentation. For laser intensities approaching I (cid:2) 1024 W/cm2, the direct laser acceleration of protons, along with ion Coulomb explosion, results in their injection into the acceleration phase of the compressed electron wave at the front of the laser pulses. The protons are observed to be accelerated up to 10–20 GeV with densities around a few times the critical density. The effect qualitatively depends on initial density and laser intensity, disappearing with the initial density increase or intensity decrease.
关键词： particle acceleration,hole-boring,overdense plasma,laser pulses,relativistic transparency
更新于2025-09-11 14:15:04
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Improving the efficiency and stability of inverted perovskite solar cells by CuSCN-doped PEDOT:PSS
摘要： Hole transport layer (HTL) is important in inverted perovskite solar cells (PSCs) to facilitate the hole extraction and suppress the charge recombination for high device performance. Based on the widely used HTL material of poly(ethylenedioxythiophene) (PEDOT):poly(styrenesulfonate) (PSS), we proposed a new HTL modification method using the widely available copper(I) thiocyanate (CuSCN); the doping of CuSCN NH3 [aq] in PEDOT:PSS followed by low-temperature annealing results in reduced energy barrier, improved charge extraction efficiency and increased the mean size of perovskite crystal of the PEDOT:PSS-CuSCN HTL-based inverted PSCs. Significantly improved device performance was observed with open current voltage over 1.0 V and power conversion efficiency (PCE) up to 15.3%, which is 16% higher in PCE than that of the PEDOT:PSS-based PSCs. More impressively, with a lower acidity than PEDOT:PSS, the PEDOT:PSS-CuSCN HTL enables excellent long-term stability of the inverted PSCs, exhibiting almost doubly improved device stability at the same storage condition. Thus, the successful application of CuSCN doping in PEDOT:PSS HTLs should provide a novel approach for the development of high-performance HTLs for highly efficient and stable PSCs.
关键词： Perovskite solar cells,Power conversion efficiency,CuSCN,Hole transport layer,Stability
更新于2025-09-11 14:15:04
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Effect of Metal Electrodes on Aging-Induced Performance Recovery in Perovskite Solar Cells
摘要： For commercialization of perovskite solar cells, it is important to substitute the alternative electrode for Au to decrease the unit cost. From the early stage, Ag exhibits a potential to be a good counter electrode in perovskite solar cells, however there is an abnormal s-shaped J-V curve with Ag electrode, and it is recovered as time passed. The perception of the aging-induced recovery process and refutation for raised stability issues are required to commercial application of Ag electrodes. Herein, we compared the aging effect of perovskite solar cells with Ag and Au electrodes and found that only devices with Ag electrodes have dramatical aging-induced recovery process. We observed the change of photo-electronic properties only in the devices with Ag electrodes as time passes which mainly contribute to recovery of s-shaped J-V curve. We verified the work function change of aged Ag electrode and its mechanism by photoelectron spectroscopy analysis. By comparing the light stability under 1-sun intensity illumination we can assure the practical stability of Ag electrodes in case of being encapsulated. This work suggests the profound understanding of aging-induced recovery process of perovskite solar cells, and the possibility of commercial application of Ag electrodes.
关键词： Perovskite solar cells,Hole injection,Interfacial reaction,Metal electrodes,Work function
更新于2025-09-11 14:15:04
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Side-Chain Engineering of Donor–Acceptor Conjugated Small Molecules As Dopant-Free Hole-Transport Materials for Efficient Normal Planar Perovskite Solar Cells
摘要： Simultaneously improving efficiency and stability, which are particularly crucial factors for the commercialization of perovskite solar cells (PSCs), remains a major challenge. For high efficiency normal PSCs, the development of stable dopant-free hole-transport materials (HTMs) seems imperative. Here, we developed potential donor-acceptor (D-A) small molecules (BTTI) as HTMs for normal planar PSCs. Through tailoring its alkyl side chain length as BTTI-C6, BTTI-C8 and BTTI-C12, our results show that upon shortening the side chain of BTTI, the hole mobility, film-forming capability and resultant device performance were remarkably improved, with device conversion efficiencies of 19.69% for BTTI-C6, 18.89% for BTTI-C8 and 17.49% for BTTI-C12. Meanwhile, compared to those made with the routine doped Spiro-OMeTAD, devices based on our dopant-free HTMs exhibited significantly improved stability. This work paves the way to the development of effective dopant-free HTMs for high performance PSCs.
关键词： Perovskite solar cells,Donor-acceptor conjugated small molecules,Dopant-free,Hole-transport materials,Side chain engineering
更新于2025-09-11 14:15:04
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Large-area near-infrared perovskite light-emitting diodes
摘要： The performance of perovskite light-emitting diodes (PeLEDs) has progressed rapidly in recent years, with electroluminescence efficiency now reaching 20%. However, devices, so far, have featured small areas and usually show notable variation in device-to-device performance. Here, we show that the origin of suboptimal device performance stems from inadequate hole injection, and that the use of a hole-transporting polymer with a shallower ionization potential can improve device charge balance, efficiency and reproducibility. Using an ITO/ZnO/PEIE/FAPbI3/poly-TPD/MoO3/Al device structure, we report a 799 nm near-infrared PeLED that operates with an external quantum efficiency (EQE) of 20.2%, at a current density of 57 mA cm?2 and a radiance of 57 W sr?1 m?2. The standard deviation in the device EQE is only 1.2%, demonstrating high reproducibility. Large-area devices measuring 900 mm2 operate with a high EQE of 12.1%, and are shown to suit medical applications such as subcutaneous deep-tissue illumination and heart rate monitoring.
关键词： near-infrared,hole injection,medical applications,perovskite light-emitting diodes,large-area
更新于2025-09-11 14:15:04
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Suppressing Interfacial Dipoles to Minimize Open‐Circuit Voltage Loss in Quantum Dot Photovoltaics
摘要： Quantum-dot (QD) photovoltaics (PVs) offer promise as energy-conversion devices; however, their open-circuit-voltage (VOC) deficit is excessively large. Previous work has identified factors related to the QD active layer that contribute to VOC loss, including sub-bandgap trap states and polydispersity in QD films. This work focuses instead on layer interfaces, and reveals a critical source of VOC loss: electron leakage at the QD/hole-transport layer (HTL) interface. Although large-bandgap organic materials in HTL are potentially suited to minimizing leakage current, dipoles that form at an organic/metal interface impede control over optimal band alignments. To overcome the challenge, a bilayer HTL configuration, which consists of semiconducting alpha-sexithiophene (α-6T) and metallic poly(3,4-ethylenedioxythiphene) polystyrene sulfonate (PEDOT:PSS), is introduced. The introduction of the PEDOT:PSS layer between α-6T and Au electrode suppresses the formation of undesired interfacial dipoles and a Schottky barrier for holes, and the bilayer HTL provides a high electron barrier of 1.35 eV. Using bilayer HTLs enhances the VOC by 74 mV without compromising the JSC compared to conventional MoO3 control devices, leading to a best power conversion efficiency of 9.2% (>40% improvement relative to relevant controls). Wider applicability of the bilayer strategy is demonstrated by a similar structure based on shallow lowest-unoccupied-molecular-orbital (LUMO) levels.
关键词： band engineering,quantum dot solar cells,interfacial dipole,hole transport layers
更新于2025-09-11 14:15:04
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Low‐Cost and Highly Efficient Carbon‐Based Perovskite Solar Cells Exhibiting Excellent Long‐Term Operational and UV Stability
摘要： Today’s perovskite solar cells (PSCs) mostly use components, such as organic hole conductors or noble metal back contacts, that are very expensive or cause degradation of their photovoltaic performance. For future large-scale deployment of PSCs, these components need to be replaced with cost-effective and robust ones that maintain high efficiency while ascertaining long-term operational stability. Here, a simple and low-cost PSC architecture employing dopant-free TiO2 and CuSCN as the electron and hole conductor, respectively, is introduced while a graphitic carbon layer deposited at room temperature serves as the back electrical contact. The resulting PSCs show efficiencies exceeding 18% under standard AM 1.5 solar illumination and retain ≈95% of their initial efficiencies for >2000 h at the maximum power point under full-sun illumination at 60 °C. In addition, the CuSCN/carbon-based PSCs exhibit remarkable stability under ultraviolet irradiance for >1000 h while under similar conditions, the standard spiro-MeOTAD/Au based devices degrade severely.
关键词： inorganic hole conductor,perovskite solar cells,efficiency,stability,carbon
更新于2025-09-11 14:15:04
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Exploring Electronic and Excitonic Processes Towards Efficient Deep Red CuInS2/ZnS Quantum-dot Light-emitting Diodes
摘要： The electroluminescence mechanisms in the Cd-free CuInS2/ZnS quantum-dot based light-emitting diodes (QLEDs) are systematically investigated through transient electroluminescence measurements. The results demonstrate that the characteristics of hole transporting layers (HTLs) determine the QLEDs to be activated by the direct charge-injection or the energy-transfer. Moreover, both the energy level alignment between HTL and quantum dot and the carrier mobility properties of the HTLs are critical factors to affect the device performance. By choosing suitable HTL, such as 4,4'-bis(9-carbazolyl)-2,2'-biphenyl, highly efficient deep red (emission peak at ~650 nm) CuInS2/ZnS QLEDs based on single HTL can be obtained with peak current efficiency and luminance of ~2.0 cd/A and nearby 3000 cd/m2, respectively.
关键词： energy transfer,charge injection,hole-transport layer,QLEDs,electron leakage,charge accumulation
更新于2025-09-11 14:15:04
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Simulation of the Sb<sub>2</sub>Se<sub>3</sub> solar cell with a hole transport layer
摘要： A model of the Sb2Se3 solar cell with a hole transport layer (HTL) has been investigated by solar cell capacitance simulator (SCAPS). The influence of different HTLs on device performance has been firstly analyzed, and CuO has been found to be the best HTL. Then, Sb2Se3 thickness, CuO thickness, the doping concentration of HTLs on device performance has been firstly analyzed, and CuO has been found to be the best HTL. Then, Sb2Se3 thickness, CuO thickness, the doping concentration of CuO, the hole mobility of CuO, the defect density of Sb2Se3 layer, the defect density at the CdS/Sb2Se3 interface, and the work function of metal electrode on device performance have been systematically studied. The optimum thicknesses of Sb2Se3 and CuO are 300 nm and 20 nm, respectively. To achieve ideal performance, the doping concentration of CuO should be more than 1019cm-3, and its hole mobility should be over 1 cm2V-1s-1. The defect densities in the Sb2Se3 layer and at the CdS/Sb2Se3 interface play a critical role on device performance, both of which should be as low as 1013 cm-3 and 1014 cm-2, respectively. In addition, the work function of the metal electrode should be more than 4.8 eV to avoid formation of Schottky junction at the metal electrode interface. After optimization, a best efficiency of 23.18% can be achieved. Our simulation results provide valuable information to further improve the efficiency of Sb2Se3 solar cells in practice.
关键词： Sb2Se3 solar cell,hole transport layer,SCAPS
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Double-Heterodyne Detection of Spectral Hole in Rare Earth Doped Crystal for Laser Frequency Stabilization and Opto-Mechanical Sensing
摘要： Laser frequency stabilization is nowadays mainly dominated by the use of high finesse Fabry-Perot cavities (FPC). However, recently developed optical lattice clocks show performances that are limited by the instability of the cavity used to stabilize the probe laser frequency owing to the brownian motion of the cavity elements. On the other hand, Spectral Hole Burning appears to be a good alternative to cavities for laser frequency stabilization. At cryogenic temperature, a narrow spectral feature can be generated in the inhomogeneously broadened absorption spectrum of Eu3+ : Y2SiO5 around 580 nm by saturating absorption close to a given frequency. This spectral hole exhibits relatively low environmental sensitivity and lower frequency drift rates compared to the resonant modes of a room-temperature FPC [1,2]. Since the probed ions are embedded in a crystalline matrix which is maintained at low temperature (typically below 7 K), the residual noise due to brownian motion is expected to be several orders of magnitude lower than the corresponding effect arising in an amorphous FPC at room temperature. We present here a novel technique of probing spectral holes in order to derive a suitable error signal for frequency stabilization based on double-heterodyne detection, that allowed us to obtain a stability at 1160nm as low as 1.5 × 10?15 for 1 s integration time (more than one order of magnitude lower than previous results obtained on our setup [3]). This setup relies on a closed cycle pulse-tube cryostat to maintain the crystal at 3.2 K and two lasers to obtain an error signal from spectral hole. The first laser (master) is pre-stabilized on a commercial FPC and used as a reference with frequency out of the absorption curve. The second laser (slave) is offset phase locked to the master such that its frequency is around the absorption maximum. A narrow (4 kHz FWHM) hole is burned with a short (500 ms, 20 μW/cm2) pulse of the slave laser and then continuous wave light (100 nW of the slave light, 1 mW of the master light) is applied. Fast Si photodiodes are used to obtain a beatnote between master and slave whose phase depends on the slave frequency detuning with respect to the hole center. Since our digitally implemented driving of the slave frequency allows us to generate arbitrary spectral features (in the MHz range around center frequency), we implemented a “dual frequency” probing scheme that uses one frequency to probe the hole, and the other as a reference. With this scheme, we manage to reduce noise source coming from the RF signal processing as well as time jitter between the two inputs of the acquisition board. The versatility of this error signal generation technique makes it possible to probe multiple narrow holes at the same time as a way to improve the signal to noise ratio. Such development will be implemented in the near future to decrease the detection noise level. In addition, our opto-electronical system allows to perform high precision metrology on spectral holes. We here show first results concerning the measurement of opto-mechanical coupling between the hole frequency and uni-axial mechanical constraints applied to the crystal. To do so, we designed a mechanical setup applying controlled pressure shifts on the crystal and then measure the hole position and shape. This characterization is a first step toward a measurement of the behavior of a micro-resonator (a 100 μm × 10 μm × 10 μm cantilever) carved into the crystal [4]. To achieve such a measurement, a low level of detection noise as well as a high locking bandwidth of the slave frequency to the hole are required which is driving future development of the experiment.
关键词： laser frequency stabilization,opto-mechanical sensing,spectral hole burning,double-heterodyne detection
更新于2025-09-11 14:15:04