- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Low temperature platinum chemical vapor deposition on functionalized self-assembled monolayers
摘要： The reaction pathways of Pt CVD using (COD)PtMe2 – xClx (x = 0, 1, 2) have been investigated on functionalized self-assembled monolayers (SAMs) as models for organic substrates. Residual gas analysis for (COD)PtMe2 and (COD)PtMeCl is consistent with the loss of methyl radicals as the initial step in deposition, while for (COD)PtCl2, the first step is the loss of a chlorine radical. It is further shown using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry that the deposition process leads to chemical damage of the SAM layer and little Pt deposition. Using this understanding, it is demonstrated that the Pt CVD rate can be controlled using a radical trap. In the presence of 1,4-cyclohexadiene, a well-known alkyl radical trap, Pt deposition was increased by 5× to 10×, creating a room-temperature effective Pt CVD process.
关键词： time-of-flight secondary ion mass spectrometry,x-ray photoelectron spectroscopy,Pt CVD,chemical vapor deposition,self-assembled monolayers,radical trap
更新于2025-09-23 15:21:01
-
Surface Passivation of Perovskite Film by Sodium Toluenesulfonate for Highly Efficient Solar Cells
摘要： Ionic defects at the surfaces of organolead halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells (PSCs). Herein, sodium p-toluenesulfonate (STS) is applied during the surface modification of perovskite layer for the first time, leading to the efficient surface passivation of the perovskite film and consequently significant enhancements in both efficiency and stability of mixed-cation PSC devices. Upon incorporating STS atop the perovskite layer, the power conversion efficiency of the Cs0.05MA0.12FA0.83PbI2.55Br0.45 (abbreviated as CsMAFA) mesoporous-structure mixed-cation PSC devices improves from 18.70% to 20.05% with reduced hysteresis. The sulfonate (–SO3–) anion of STS coordinates with the Pb2+ of CsMAFA perovskite, and the Na+ cation of STS electrostatically interacts with the anions (I–/Br–) of CsMAFA perovskite, resulting in the surface passivation of the CsMAFA perovskite film with reduced electron and hole trap state densities. In addition, STS modification induces an upshift of the valence band of perovskite, facilitating hole extraction from the perovskite layer to the hole transport layer with suppressed interfacial charge recombination. Moreover, such a trap state passivation of perovskite film leads to improvement of the ambient stability of PSC devices.
关键词： ionic defects,trap state passivations,perovskite solar cells,surface modifications,charge extractions
更新于2025-09-23 15:21:01
-
Facet Control for Trap-State Suppression in Colloidal Quantum Dot Solids
摘要： Trap states in colloidal quantum dot (QD) solids significantly affect the performance of QD solar cells, because they limit the open-circuit voltage and short circuit current. The {100} facets of PbS QDs are important origins of trap states due to their weak or missing passivation. However, previous investigations focused on synthesis, ligand exchange, or passivation approaches and ignored the control of {100} facets for a given dot size. Herein, trap states are suppressed from the source via facet control of PbS QDs. The {100} facets of ≈3 nm PbS QDs are minimized by tuning the balance between the growth kinetics and thermodynamics in the synthesis. The PbS QDs synthesized at a relatively low temperature with a high oversaturation follow a kinetics-dominated growth, producing nearly octahedral nanoparticles terminated mostly by {111} facets. In contrast, the PbS QDs synthesized at a relatively high temperature follow a thermodynamics-dominated growth. Thus, a spherical shape is preferred, producing truncated octahedral nanoparticles with more {100} facets. Compared to PbS QDs from thermodynamics-dominated growth, the PbS QDs with less {100} facets show fewer trap states in the QD solids, leading to a better photovoltaic device performance with a power conversion efficiency of 11.5%.
关键词： solar cells,trap-state suppression,quantum dots,facet control
更新于2025-09-23 15:21:01
-
Low impact of two LED colors on nocturnal insect abundance and bat activity in a peri-urban environment
摘要： Artificial light at night (ALAN) is an important driver of change in ecological environments of the 21th century. We investigated the impact on nocturnal insect abundance and bat activity of two LED light colors (warm-white 2700 K, cold-white 6500 K) in a peri-urban environment. Bat activity (predominantly Pipistrellus pipistrellus) was largely driven by prey availability (insects), while insect abundance was responsive to nightly weather conditions (precipitation, temperature). Thus, both insects and bats were not differentially responsive to cold-white or warm-white LEDs. These findings are largely in contrast with literature, particularly for insects. However, as most published experiments on ALAN were conducted in areas that were lit solely for the purpose of the experiment, we would like to bring forward that (1) adaptation to environmental constraints may play a role in peri-urban environments that have been exposed to ALAN for many decades; or (2) impacts of cold-white LEDs on nocturnal insects may be lower than expected, because nocturnal insects adapted to low-light conditions may be put off by cold white light sources (6500 K).
关键词： Artificial light at night; ALAN,Light pollution,Impact assessment,Flight-intersection trap,Batlogger
更新于2025-09-23 15:21:01
-
Characteristics of a magneto-optical trap of molecules
摘要： We present the properties of a magneto-optical trap (MOT) of CaF molecules. We study the process of loading the MOT from a decelerated buffer-gas-cooled beam, and how best to slow this molecular beam in order to capture the most molecules. We determine how the number of molecules, the photon scattering rate, the oscillation frequency, damping constant, temperature, cloud size and lifetime depend on the key parameters of the MOT, especially the intensity and detuning of the main cooling laser. We compare our results to analytical and numerical models, to the properties of standard atomic MOTs, and to MOTs of SrF molecules. We load up to 2 × 10^4 molecules, and measure a maximum scattering rate of 2.5 × 10^6 s^?1 per molecule, a maximum oscillation frequency of 100 Hz, a maximum damping constant of 500 s^?1, and a minimum MOT rms radius of 1.5 mm. A minimum temperature of 730 μK is obtained by ramping down the laser intensity to low values. The lifetime, typically about 100 ms, is consistent with a leak out of the cooling cycle with a branching ratio of about 6 × 10^?6. The MOT has a capture velocity of about 11 m s^?1.
关键词： magneto-optical trap,ultracold molecules,laser-cooled molecules
更新于2025-09-23 15:21:01
-
Nanoscale virtual potentials using optical tweezers
摘要： We combine optical tweezers with feedback to impose arbitrary potentials on a colloidal particle. The feedback trap detects a particle’s position, calculates a force based on an imposed “virtual potential,” and shifts the trap center to generate the desired force. We create virtual harmonic and double-well potentials to manipulate particles. The harmonic potentials can be chosen to be either weaker or stiffer than the underlying optical trap. Using this ?exibility, we create an isotropic trap in three dimensions. Finally, we show that we can create a virtual double-well potential with ?xed well separation and adjustable barrier height. These are accomplished at length scales down to 11 nm, a feat that is dif?cult or impossible to create with standard optical-tweezer techniques such as time sharing, dual beams, or spatial light modulators.
关键词： optical tweezers,colloidal particle,virtual potential,nanoscale,feedback trap
更新于2025-09-23 15:21:01
-
states of Rb in simultaneous magneto-optical trapping of Rb and Hg
摘要： We report the measurement of the photoionization cross sections of the 5S1/2 and 5P3/2 states of 87Rb in a two-species Hg and Rb magneto-optical trap (MOT) by the cooling laser for Hg. The photoionization cross sections of Rb in the 5S1/2 and 5P3/2 states at 253.7 nm are determined to be 1+4.3 × 10?20 cm2 and 4.63(30) × 10?18 cm2, respectively. To measure the 5S1/2 and 5P3/2 state fractions in the MOT we detected the photoionization rate of the 5P3/2 state by an additional 401.5 nm laser. The photoionization cross section of Rb in the 5P3/2 state at 401.5 nm is determined to be 1.18(10) × 10?17 cm2.
关键词： Hg,laser cooling,Rb,magneto-optical trap,photoionization cross sections
更新于2025-09-23 15:21:01
-
The influence of fullerene on hysteresis mechanism in planar perovskite solar cells
摘要： Despite the rapid development of perovskite devices, the current density-voltage hysteresis still needs to be conquered. Here, the introduction of PCBM into the active layer of planar perovskite solar cells is carried out and hysteresis-free devices are produced. A photoluminescence blue-shift in PCBM-doped perovskite ?lms is observed. The e?ect of non-radiative recombination is obviously suppressed, and the photoluminescence lifetime is signi?cantly prolonged by 3-fold after PCBM introduction. The roles of PCBM in trap states and hysteresis mechanism are also discussed. This research could provide experimental and theoretical supports for suppressing and eliminating the hysteresis phenomena in perovskite solar cells.
关键词： Hysteresis,Trap states,Planar perovskite solar cells,PCBM
更新于2025-09-23 15:19:57
-
Research on Degradation of GaN-Based Blue LED Caused by <i>?3</i> Radiation under Low Bias
摘要： GaN multiquantum-well blue light-emitting diodes (LEDs) were radiated with 60Co c-rays for accumulated doses up to 2.5 Mrad (SiO2). The radiation-induced current and 1/f noise degradations were studied when the devices operate at the low bias voltage. The current increased by 2.31 times, and the 1/f noise increased by 275.69 times after a dose of 2.5 Mrad (SiO2). Based on Hurkx’s trap-assisted tunneling model, the degradation of current was explained. c radiation created defects in the space-charge region of LEDs. These defects as generation-recombination centers lead to the increase in the current. In addition, based on the quantum l/f noise theory, the degradation of 1/f noise might be also attributed to these defects, which caused an increase in the Hooge constant and a decrease in the carrier lifetimes. The current and 1/f noise degradations can be attributed to the same physical origin. Compared to the current, the 1/f noise parameter is more sensitive, so it may be used to evaluate the radiation resistance capability of GaN blue LEDs.
关键词： Hooge constant,current degradation,1/f noise degradation,trap-assisted tunneling,γ radiation,GaN,LED
更新于2025-09-23 15:19:57
-
The diverse passivation effects of fullerene derivative on hysteresis behavior for normal and inverted perovskite solar cells
摘要： [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is usually used to passivate the trap states and ion defects for suppressing hysteresis in both normal and inverted perovskite solar cells. Here, we find that the normal cell with the perovskite film fabricated on the PCBM film shows an evident hysteresis, while the inverted cell with the perovskite film covered by the PCBM film shows nearly no hysteresis, and the PCBM-Perovskite interface impacts on the hysteresis vastly. The poor PCBM surface wettability results in an inefficient carrier extraction at the interface and a red-shift of photoluminescence emission for the perovskite film coated on the PCBM film, which results from the plentiful trap states and ion defects inside the perovskite film due to its poor crystallization. Thus, the trapping/de-trapping processes and slow ion migration eventually lead to the hysteresis. For the perovskite film covered by the PCBM film, due to the good wettability of the perovskite film, PCBM molecules easily permeate into the perovskite film to passivate the trap states and ion defects, which improves the carrier extraction and thus eliminates the hysteresis of the inverted cell.
关键词： Hysteresis behavior,Trap states,Perovskite solar cells,Ion migration,Carrier extraction,PCBM
更新于2025-09-23 15:19:57