- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
RbF modified FTO electrode enable energy-level matching for efficient electron transport layer-free perovskite solar cells
摘要： The development of highly efficient electron transport layer free perovskite solar cells (ETL-free PSCs) with simplified and economical device configurations can significantly motivate the commercialization of PSCs. However, the performance of ETL-free PSCs has been hampered by the sluggish charge extraction and severe charge carrier recombination due to the energy-level mismatch at the interface of the perovskite and the transparent conductive electrode FTO (fluorine doped tin-oxide). In this study, this issue is well solved by modifying the FTO surface with a simple, low-cost and non-toxic rubidium fluoride (RbF) interlayer. An interfacial dipole layer is formed on the FTO surface by inserting a RbF layer, which tunes the work function of FTO, eliminates the electron transport barrier and optimizes the energy-level alignment at the FTO/perovskite interface, thereby enhancing the charge transfer and suppressing the carrier recombination. Consequently, the rigid ETL-free PSCs with RbF layer yield high efficiencies of up to 18.79%, higher than that of ETL-free devices on bare FTO (16.03%). By virtue of the low-temperature processability, a superior PCE of 15.7% has been achieved by flexible ETL-free PSCs fabricated on RbF modified plastic substrate. This study provides a simple, efficient and environmentally friendly approach to modify the FTO electrode for fabricating ETL-free PSCs, which contribute to promote the design of advanced interface materials for simplified and high-performance perovskite photovoltaics.
关键词： ETL-Free Perovskite Solar Cells,Interface Dipole,Energy-Level Matching,Aqueous Processing
更新于2025-09-23 15:21:01
-
Arbitrary control of the diffusion potential between a plasmonic metal and a semiconductor by an angstrom-thick interface dipole layer
摘要： Localized surface plasmon resonances (LSPRs) are gaining considerable attention due to the unique far-field and near-field optical properties and applications. Additionally, the Fermi energy, which is the chemical potential, of plasmonic nanoparticles is one of the key properties to control hot-electron and -hole transfer at the interface between plasmonic nanoparticles and a semiconductor. In this article, we tried to control the diffusion potential of the plasmonic system by manipulating the interface dipole. We fabricated solid-state photoelectric conversion devices in which gold nanoparticles (Au-NPs) are located between strontium titanate (SrTiO3) as an electron transfer material and nickel oxide (NiO) as a hole transport material. Lanthanum aluminate as an interface dipole layer was deposited on the atomic layer scale at the three-phase interface of Au-NPs, SrTiO3, and NiO, and the effect was investigated by photoelectric measurements. Importantly, the diffusion potential between the plasmonic metal and a semiconductor can be arbitrarily controlled by the averaged thickness and direction of the interface dipole layer. The insertion of an only one unit cell (uc) interface dipole layer, whose thickness was less than 0.5 nm, dramatically controlled the diffusion potential formed between the plasmonic nanoparticles and surrounding media. This is a new methodology to control the plasmonic potential without applying external stimuli, such as an applied potential or photoirradiation, and without changing the base materials. In particular, it is very beneficial for plasmonic devices in that the interface dipole has the ability not only to decrease but also to increase the open-circuit voltage on the order of several hundreds of millivolts.
关键词： interface dipole,Fermi energy,strontium titanate,nickel oxide,hole transfer,hot-electron,lanthanum aluminate,gold nanoparticles,photoelectric conversion,Localized surface plasmon resonances
更新于2025-09-23 15:19:57
-
Work Function-Tunable Graphene-Polymer Composite Electrodes for Organic Light-Emitting Diodes
摘要： Graphene has been regarded as one of the most promising transparent electrodes in flexible optoelectronic devices. Tremendous efforts have been paid on tuning the work function of graphene, which make significant contributions to improve the device performance. In this work, we propose to modify single layer graphene film with ultrathin high dielectric polymers, including polyvinylidene chloride (PVDC) and polyvinylidene difluoride (PVDF) with the dielectric constants of 4.7 and 8.4, respectively. Ultraviolet photoelectron spectroscopy confirms the formation of interfacial dipoles induced by the high dielectric polymers, and the work function can be tuned from 4.6 eV for pristine graphene to 4.72 and 4.94 eV for PVDF and PVDC modified graphene, respectively. Accordingly, organic light-emitting diodes (OLEDs) are fabricated, and the one based on PVDC-modified graphene composite electrode obtained the highest current efficiency of 80.0 cd/A with a 1.27-fold enhancement compared with the pristine counterpart. This work provides an alternative strategy of interfacial dipole to surface chemical doping method to tune the work function of graphene electrodes, and the utilization of a polymer with high dielectric constant to modify graphene successfully realized the fabrication of highly efficient OLEDs.
关键词： graphene,work function,high dielectric polymer,interface dipole,OLEDs
更新于2025-09-23 15:19:57
-
Role of Molecular and Interchain Ordering in the Formation of a δ-Hole Transporting Layer in Organic Solar Cells
摘要： Interface engineering, especially the realisation of ohmic contacts at the interface between organic semiconductors and metal contacts, is one of the essential preconditions to achieve high efficiency organic electronic devices. Here, the interface structure of polymer/fullerene blends are correlated with the charge extraction/injection properties of working organic solar cells. The model system – P3HT:PCBM – is fabricated using two different degrees of P3HT regioregularity to alter the blend interchain order and molecular packing, resulting in different device performance. Investigations by electroabsorption (EA) spectroscopy on these devices indicate a significant reduction (≈ 1 V) in the built-in potential with an increase in the P3HT regioregularity. This observation is also supported by a change in the WF of high regioregular polymer blends from photoelectron spectroscopy measurement. These results confirm the presence of a strong dipole layer acting as a δ-hole transporting layer at the polymer/MoO3/Ag electrode interface. Unipolar hole-only devices show an increase in the magnitude of the hole current in high regioregular P3HT devices, suggesting an increase in the hole injection/extraction efficiency inside device with a δ-hole transporting layer. Microscopically, near edge X-ray absorption fine structure (NEXAFS) spectroscopy was conducted to probe the surface microstructure in these blends finding a highly edge-on orientation of P3HT chains in blends made with high regioregular P3HT. This edge-on orientation of P3HT chains at the interface results in a layer of oriented alkyl side chains capping the surface which favors the formation of a dipole layer at the polymer/MoO3 interface. The increase in the charge extraction efficiency due to the formation of a δ-hole transporting layer thus results in higher short circuit currents and fill factor values, eventually increasing the device efficiency in high regioregular P3HT devices despite a slight decrease in cell open circuit voltage. These findings emphasise the significance of work function control as a tool for improved device performance, and pave the way towards interfacial optimisation based on the modulation of fundamental polymer properties, such as polymer regioregularity.
关键词： Organic solar cells,interface engineering,molecular ordering,regioregularity,interface dipole,interchain ordering,P3HT
更新于2025-09-12 10:27:22
-
Mechanism of Organic Solar Cell Performance Degradation upon Thermal Annealing of MoO <sub/>x</sub>
摘要： In this work we focus on P3HT:PC61BM bulk heterojunction (BHJ) devices with MoO3 at the hole extraction side of the BHJ which relies on the formation of a strong dipole at the BHJ/MoO3 interface, as a reference system that has been extensively studied. We have observed depending on when the annealing is performed during device fabrication, device performance either increased or decreased due to formation of a sharp or relatively diffuse interface respectively due to diffusion of MoOx into the BHJ. The measured strength of the dipole at this interface following thermal annealing correlated well with the width of the interface and device performance, with the sharper interface resulting in a stronger dipole and in improved device performance. This is expected to be a general phenomenon for evaporated coatings onto polymeric BHJ, regardless of the polymers involved.
关键词： Organic solar cell,Interface dipole,MoO3,Thermal annealing,Energy level alignment
更新于2025-09-12 10:27:22
-
The Influence of Moisture on the Energy Level Alignment at the MoO <sub/>3</sub> /Organic Interfaces
摘要： MoO3 is widely used in polymer-based organic solar cells as an anode buffer layer due to its high workfunction and formation of a strong dipole at the MoO3/polymer interface facilitating the charge transfer across the MoO3/polymer interface. In the present work we show that exposure of the MoO3/polymer interface to moisture attracts water molecules to the interface via diffusion. Due to their own strong dipole water molecules counter the dipole at the MoO3/polymer interface. As a consequence, the charge transfer across the MoO3/polymer will reduce and affect the charge transport across the interface. The outcome of this work thus suggest that it is critical to keep the MoO3/polymer interface moisture free which requires special precautions in device fabrications. The composition of the MoO3/P3HT:PC61BM interface is analyzed with X-ray photoelectron spectroscopy and the depth profiling technique neutral impact collision ion scattering spectroscopy. The results show that the concentration of oxygen increases upon exposure but leave the oxidation state of the Mo unchanged. Valence electron spectroscopy technique shows that the dipole across the MoO3/P3HT:PC61BM interface decreases even for short time exposure to atmosphere due to the diffusion of water molecules to the interface. The far-ranging consequences for organic electronic devices are discussed.
关键词： exposure to air,interface,dipole formation,electron spectroscopy,metal oxide,organic photovoltaic,conjugated polymer
更新于2025-09-11 14:15:04