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Solution-processed blue quantum-dot light-emitting diodes based on double hole transport layers: Charge injection balance, solvent erosion control and performance improvement
摘要： Solution processed quantum-dot based light emitting diodes (QLEDs) usually suffer from the issues of imbalanced carrier injection (especially for blue QLEDs) and solvent erosion, which prevents these devices from reaching high performance. Here we report a simple and effective method of promoting hole injection and mitigating solvent erosion simultaneously for fabricating high-performance blue QLEDs. Poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))-diphenylamine)] (TFB)/Lithium bis(trifluoromethanesulfonimide) (Li-TFSI)-doped poly(9-vinlycarbazole) (PVK) bi-layers with smooth surfaces/interfaces, prepared via a solution-process by utilizing 1,4-dioxane as the solvent for PVK, were used as hole transport layers (HTLs) for improving the performance of blue QLEDs. The TFB/Li-doped PVK based QLED records 5829 cd/m2 of maximum brightness and 5.37% of peak EQE, which represents 1.1-fold increase in brightness and ~11.5-fold increase in EQE as compared with the devices based on TFB-only HTLs. The enhanced performance for these TFB/Li-doped PVK based QLEDs can be ascribed to more efficient hole injection offered by Li-doped bilayer HTLs with smooth surfaces/interfaces and stepwise energy level alignment. The CIE 1931 color coordinates (0.15, 0.03) for these TFB/Li-doped PVK based QLEDs are close to the National Television System Committee (NTSC) standard blue CIE coordinates, showing promise for use in next-generation full-color displays. This work provides a facile solution method of fabricating TFB/Li-doped PVK bi-layers with smooth surfaces/interfaces and proves the superiority of these TFB/Li-doped PVK bi-layered HTLs in hole transport and injection for high-performance blue QLEDs.
关键词： double hole transport layers,blue quantum-dot light-emitting diodes,charge injection；Lithium salt doped hole transport layer,solvent erosion,solution processability
更新于2025-09-23 15:19:57
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Performance optimization of CH3NH3Pb(I1-xBrx)3 based perovskite solar cells by comparing different ETL materials through conduction band offset engineering
摘要： Numerical simulations can provide the physical insights into the carrier transport mechanism in the solar cells, and the factors influencing their performance. In this paper, perovskite solar cell (PSC) based on the mixed perovskite (CH3NH3Pb(I1-xBrx)3 has been numerically simulated using the SCAPS simulator. A comparative analysis of different electron transport layers (ETLs) based on their conduction band offsets (CBO) has been performed, while Spiro-OMeTAD was used as a hole transport layer (HTL). Among the proposed ETLs, CdZnS performed better and demonstrated the power conversion efficiency (PCE) of 25.20%. Also, the PCE of the PSC has been optimized by adjusting the doping concentrations in the ETL, Spiro-OMeTAD layer, and the thickness of the perovskite light absorber layer. It was found that the doping concentration of 1021 cm?3 for the CdZnS based ETL and 1020 cm?3 for Spiro-OMeTAD are the optimum concentrations values for demonstrating enhanced efficiency. A 600 nm thick perovskite layer has found to be appropriate for the efficient PSC design. For the initial guessing and numerical model validation, the photovoltaic data of a very stable (over one year with PCE ~13%) n-i-p structured (ITO/TiO2/CH3NH3Pb(I1-xBrx)3/Spiro-OMeTAD/Au) PSCs was used. These numerically simulated results signify the optimum performance of the photovoltaic device that can be further implemented to develop the highly efficient PSCs.
关键词： The power conversion efficiency,Hole transport layer,Electron transport layer,Conduction band offset engineering,SCAPS,Perovskite solar cell
更新于2025-09-23 15:19:57
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Semi-Transparent Perovskite Solar Cells with a Cross-Linked Hole Transport Layer
摘要： Semi-transparent perovskite solar cells (ST-PeSCs) have received great attention because of their excellent performance and promising application in areas such as tandem devices and building integrated photovoltaics (BIPVs). Critical across all these applications is achieving both high efficiency and stable photovoltaic performance of such devices. Realizing both of these properties simultaneously has not been possible using device architectures featuring the archetypal doped Spiro-OMeTAD as a hole transport layer (HTL). As such, in this work we explore the use of a solution-processed cross-linked HTL formed from N4,N4′-di(naphthalen-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine (VNPB) molecules as an alternative to the conventional Spiro-OMeTAD within an FTO/SnO2/C60-SAM/Perovskite/HTL/MoOx/ultra-thin gold/MoOx ST-PeSC device architecture. Through an optimized multi-step thermal treatment process that maximizes charge extraction and reduces recombination from these devices, we can achieve ST-PeSCs that exhibit record power conversion efficiencies for Spiro-OMeTAD-free devices with average visible transmittance values between 10 and 30%. These devices exhibit comparable efficiencies to their Spiro-OMeTAD counterparts, with the additional benefit that the use of the poly-VNPB as the HTL material provides significant improvements in long-term device stability under both continuous illumination and high humidity conditions.
关键词： stability,perovskite solar cells,cross-linked layer,semi-transparent,hole transport layer,building integrated photovoltaics
更新于2025-09-23 15:19:57
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Decent efficiency improvement of organic photovoltaic cell with low acidic hole transport material by controlling doping concentration
摘要： Presently, poly (3, 4-ethylenedi-oxythiophene): polystyrene sulfonic acid (PEDOT:PSS) is most commonly used hole transport material (HTM) in photovoltaic (PV) cells but its higher acidity, hygroscopicity, high price have motivated people to develop a good substitute. Here, we prepare a series of PSS-doped polyaniline (PANI) with synergic (around 90%) transmittance and work function value (within 5.09-5.16 eV) varying PSS concentrations to check the possible utility as HTM in a poly (3-hexylthiophene): [6, 6]-indene-C60 bisadduct based organic photovoltaic (OPV) cell. Here, it is observed that, because of change in conductivity, the PV performance of those OPV devices is strongly dependent on the doping concentration of the HTM and, at optimized PSS concentration, PANI:PSS has higher conductivity. This facilitates better hole extraction efficiency into the PV device and results in higher short circuit current density (JSC). Therefore, the PANI:PSS-based OPV device with optimized PSS concentration exhibits same level of power conversion efficiency (PCE: 4.5±0.2 %) as a PEDOT:PSS based OPV device. Thus, a lower acidic (pH = 2.2) p-type semiconductor PANI:PSS (weight ratio = 1:1 and) can be a good alternative to highly acidic (pH = 1.7) PEDOT:PSS ( weight ratio = 1:6, Clevious Al 4083) for using as HTM in an OPV device.
关键词： Hole transport layer,Organic photovoltaic cell,Doping concentration,Poly (4-styrenesulfonic acid) doped poly (3, 4-ethylenedi-oxythiophene),Poly (4-styrenesulfonic acid) doped polyaniline
更新于2025-09-23 15:19:57
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Dual Effective Dopant Based Hole Transport Layer for Stable and Efficient Perovskite Solar Cells
摘要： Conventionally, the hydroscopic nature of Li-TFSI and low boiling point of t-BP are considered as the primary limitations of hole transport layer (HTL), ultimately affecting the power conversion efficiency (PCE) and long-term stability of perovskite solar cell (PSC). To better stress these problems, a dual functional dopant termed PFPPY is reported. The in-depth operating mechanism of PFPPY with Spiro-OMeTAD, its profound effects on overall photovoltaic performance and device physics are systematically investigated. It is observed PFPPY can simultaneously take place of t-BP and FK209 in conventional HTL. By employing PFPPY as dopant cooperating with Spiro-OMeTAD, a higher PCE of 21.38% is achieved, compared with the reference device based on t-BP and FK209-doped Spiro-OMeTAD (19.69%). More importantly, the unencapsulated PFPPY-doped device shows greatly improved stability, maintaining over 90% of its initial PCE after 600 h in 40-50% RH. These findings provide a new strategy to optimize the HTL composition for efficient and stable PSCs.
关键词： Component engineering,Hole transport layer,Novel dopant,Perovskite Solar Cells
更新于2025-09-23 15:19:57
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Improving energy level alignment by adenine for efficient and stable perovskite solar cells
摘要： NiOx has been widely used as inorganic hole-transport layers (HTLs) in highly efficient hybrid perovskite solar cells (PSCs), however, the solution deposition usually induces pinhole and poor contact with perovskite. In this work, a small organic molecule adenine was used as surface modifier on NiOx substrate for the energy level modulation. After coating adenine, a 0.1 eV energy level drop for NiOx hole-transport layer (HTL), a higher crystallinity and larger grain size of perovskite layer, and an accelerated charge transport and extraction for device were achieved. Density functional theory (DFT) calculations also confirmed that the crystal structure of perovskite on NiOx/adenine substrate was more stable. These benefits enable a higher open-circuit voltage (Voc) and short-circuit current density (Jsc) in the corresponding devices with significantly enhanced moisture and light stability. Our work provides a novel strategy for modulation of energy level alignment between HTL and perovskites in related photovoltaic and other optoelectronic devices.
关键词： crystallinity,hole transport layer,perovskite,stability,interface engineering
更新于2025-09-23 15:19:57
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Significant Enhancement in Quantum Dot Light-Emitting Device Stability via a Cascading Hole Transport Layer
摘要： This work investigates the effect of the hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The electroluminescence half-life (LT50) of QDLEDs can be improved by 25x through the utilization of a cascading HTL (CHTL) structure with consecutive steps in highest occupied molecular orbital energy level. Using this approach, a LT50 of 864,000 hours (for an initial luminance of 100 cd m-2) is obtained for red QDLEDs using a conventional core/shell QD emitter. The CHTL primarily improves QDLED stability by shifting excessive hole accumulation away from the QD/HTL interface and toward the inter-layer HTL/HTL interfaces. The wider electron-hole recombination zone in the CHTL for electrons that have leaked from the QD layer results in less HTL degradation at the QD/HTL interface. This work highlights the significant influence of the HTL on QDLED stability and represents the longest LT50 for a QDLED based on the conventional core/shell QD structure.
关键词： quantum dot,EL stability,exciton-polaron interactions,QDLED,organic hole transport layer,exciton-induced degradation
更新于2025-09-23 15:19:57
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High-performance green light-emitting diodes based on MAPbBr <sub/>3</sub> with ??-conjugated ligand
摘要： The morphology, crystal size, and trap density of perovskite films significantly affect the luminescent properties of perovskite light-emitting diodes (PeLEDs). Recently, numerous studies have been conducted on ligands that surround the surface of perovskite crystals and passivate the trap sites to improve the performance of PeLEDs. In this study, a 4-aminobenzonitrile (ABN) ligand improved the performance of methylammonium lead bromide (MAPbBr3)-based PeLEDs by reducing the MAPbBr3 crystal size to the nanoscale and reducing the trap density. Moreover, the properties of PeLEDs with ABN were further improved using a surface-modified hole-transport layer (HTL) with a hydrophilic polymer. Finally, a bright green PeLED was fabricated and exhibited the maximum luminance of 3350 cd/m2 with an external quantum efficiency of 8.85%. Therefore, it is believed that the use of proper ligands for the perovskite layer and the optimization of the charge-transport layer have great potential for the development of high-performance PeLEDs.
关键词： methylammonium lead bromide,hydrophilic polymer,conjugated ligand,surface-modified hole-transport layer,perovskite light-emitting diodes,4-aminobenzonitrile
更新于2025-09-23 15:19:57
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Influence of Charge Transport Layers on Capacitance Measured in Halide Perovskite Solar Cells
摘要： We show that capacitance-based techniques cannot be used to reliably analyze the properties of defects in the perovskite layer or at its interface due to the influence of hole-transport materials. For hole-transport-layer-free PSCs, high-frequency capacitance can be considered as the geometric capacitance for calculating the dielectric constant of the perovskite layer. We further show that the low-frequency capacitance signature can be used to calculate the activation energy of the ionic conductivity of the perovskite layer.
关键词： Halide perovskite solar cells,Dielectric constant,Hole-transport layer,Capacitance-based techniques,Ionic conductivity
更新于2025-09-23 15:19:57
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Boosting the Conversion Efficiency Over 20 % in MAPbI <sub/>3</sub> Perovskite Planar Solar Cells by Employing Solution-Processed Aluminum-Doped Nickel Oxide Hole Collector
摘要： Recently, nickel oxide (NiOx) thin films have been used as an efficient and robust hole transport layer (HTL) in inverted planar perovskite solar cells (IP-PSCs) to replace costly and unstable organic transport materials. However, the power conversion efficiency (PCE) of most IP-PSCs using NiOx HTLs is rather limited below 20 % due to insufficient electronic conductivity of the NiOx. In this work, solution-processed Al-doped NiOx (ANO) films are suggested as HTLs for low cost and stable IP-PSCs. The electrical conductivity of the NiOx film is significantly enhanced by the Al doping which effectively reduces the non-radiative recombination losses at the HTL(cid:150)perovskite interfaces and boosts hole extraction/transportation. The device with undoped NiOx shows the best PCE of 16.56 %, whereas ANO HTL (5 % doping) contributes to achieve a PCE of 20.84 %, which outperforms other CH3NH3PbI3 IP-PSCs with NiOx-based HTLs reported to date. Moreover, a reliability test (1728 h storage) shows that the performance stability is enhanced by approximately 11 % by employing ANO HTLs. This investigation into ANO HTLs provides a new guideline for the further development of highly efficient and reliable IP-PSCs using low cost and robust metal oxide HTLs.
关键词： Perovskite,Solar cells,Hole transport layer,Nickel oxide,Aluminum
更新于2025-09-23 15:19:57