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Charge extraction via graded doping of hole transport layers gives highly luminescent and stable metal halide perovskite devices
摘要： One source of instability in perovskite solar cells (PSCs) is interfacial defects, particularly those that exist between the perovskite and the hole transport layer (HTL). We demonstrate that thermally evaporated dopant-free tetracene (120 nm) on top of the perovskite layer, capped with a lithium-doped Spiro-OMeTAD layer (200 nm) and top gold electrode, offers an excellent hole-extracting stack with minimal interfacial defect levels. For a perovskite layer interfaced between these graded HTLs and a mesoporous TiO2 electron-extracting layer, its photoluminescence yield reaches 15% compared to 5% for the perovskite layer interfaced between TiO2 and Spiro-OMeTAD alone. For PSCs with graded HTL structure, we demonstrate efficiency of up to 21.6% and an extended power output of over 550 hours of continuous illumination at AM1.5G, retaining more than 90% of the initial performance and thus validating our approach. Our findings represent a breakthrough in the construction of stable PSCs with minimized nonradiative losses.
关键词： perovskite solar cells,stability,charge extraction,photoluminescence,hole transport layers,graded doping
更新于2025-11-14 15:25:21
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Solution-processed p-type nanocrystalline CoO films for inverted mixed perovskite solar cells
摘要： Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pin-hole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs0.05(FA0.83MA0.17)0.95(I0.83Br0.17)3. Inverted solar cells based on crystalline CoO films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells.
关键词： Perovskite solar cells,p-type,Cobalt oxide,Colloids,Hole transport layers
更新于2025-09-23 15:21:01
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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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Boosting Performance of Nona??Fullerene Organic Solar Cells by 2D ga??C <sub/>3</sub> N <sub/>4</sub> Doped PEDOT:PSS
摘要： The power-conversion efficiency (PCE) of single-junction organic solar cells (OSCs) has exceeded 16% thanks to the development of non-fullerene acceptor materials and morphological optimization of active layer. In addition, interfacial engineering always plays a crucial role in further improving the performance of OSCs based on a well-established active-layer system. Doping of graphitic carbon nitride (g-C3N4) into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL) for PM6:Y6-based OSCs is reported, boosting the PCE to almost 16.4%. After being added into the PEDOT:PSS, the g-C3N4 as a Bronsted base can be protonated, weakening the shield effect of insulating PSS on conductive PEDOT, which enables exposures of more PEDOT chains on the surface of PEDOT:PSS core-shell structure, and thus increasing the conductivity. Therefore, at the interface between g-C3N4 doped HTL and PM6:Y6 layer, the charge transport is improved and the charge recombination is suppressed, leading to the increases of fill factor and short-circuit current density of devices. This work demonstrates that doping g-C3N4 into PEDOT:PSS is an efficient strategy to increase the conductivity of HTL, resulting in higher OSC performance.
关键词： hole-transport layers,PEDOT:PSS,organic solar cells,g-C3N4,non-fullerene acceptors
更新于2025-09-23 15:19:57
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A Chemically Orthogonal Hole Transport Layer for Efficient Colloidal Quantum Dot Solar Cells
摘要： Colloidal quantum dots (CQDs) are of interest in light of their solution-processing and bandgap tuning. Advances in the performance of CQD optoelectronic devices require fine control over the properties of each layer in the device materials stack. This is particularly challenging in the present best CQD solar cells, since these employ a p-type hole-transport layer (HTL) implemented using 1,2-ethanedithiol (EDT) ligand exchange on top of the CQD active layer. It is established that the high reactivity of EDT causes a severe chemical modification to the active layer that deteriorates charge extraction. By combining elemental mapping with the spatial charge collection efficiency in CQD solar cells, the key materials interface dominating the subpar performance of prior CQD PV devices is demonstrated. This motivates to develop a chemically orthogonal HTL that consists of malonic-acid-crosslinked CQDs. The new crosslinking strategy preserves the surface chemistry of the active layer beneath, and at the same time provides the needed efficient charge extraction. The new HTL enables a 1.4× increase in charge carrier diffusion length in the active layer; and as a result leads to an improvement in power conversion efficiency to 13.0% compared to EDT standard cells (12.2%).
关键词： hole transport layers,colloidal quantum dots,solar cells,chemical orthogonality,surface ligands
更新于2025-09-23 15:19:57
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A facile route of preparing nickel(II) oxide thin films for high-performance inverted perovskite solar cells
摘要： Perovskite solar cells (PSCs) have been very popular in the field of photovoltaics. In the inverted PSC structure, the hole transport layer deposited before perovskite photoactive layer plays a crucial role in power conversion efficiencies (PCE) and ambient stability of device. Here, we developed a facile method of preparing NiO hole transport layers aided by polymethyl methacrylate (PMMA) for inverted perovskite solar cells. Compared with reported fabrication methods, this route has the advantages of simple, low temperature, and low-cost processing. The corresponding devices exhibited a champion power conversion efficiency (PCE) of 17.78% and good stability. Various characterizations, XRD, Raman, AFM, SEM, PL etc were carried out to confirm the superior effect of the NiO film prepared by new method. We believe that this facile route will be a significant contribution for preparing high performance inverted perovskite solar cells.
关键词： NiO hole transport layers,Perovskite solar cells,low-temperature processing,PMMA,power conversion efficiency
更新于2025-09-23 15:19:57
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17% Efficient Organic Solar Cells Based on Liquid Exfoliated WS <sub/>2</sub> as a Replacement for PEDOT:PSS
摘要： The application of liquid-exfoliated 2D transition metal disulfides (TMDs) as the hole transport layers (HTLs) in nonfullerene-based organic solar cells is reported. It is shown that solution processing of few-layer WS2 or MoS2 suspensions directly onto transparent indium tin oxide (ITO) electrodes changes their work function without the need for any further treatment. HTLs comprising WS2 are found to exhibit higher uniformity on ITO than those of MoS2 and consistently yield solar cells with superior power conversion efficiency (PCE), improved fill factor (FF), enhanced short-circuit current (JSC), and lower series resistance than devices based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and MoS2. Cells based on the ternary bulk-heterojunction PBDB-T-2F:Y6:PC71BM with WS2 as the HTL exhibit the highest PCE of 17%, with an FF of 78%, open-circuit voltage of 0.84 V, and a JSC of 26 mA cm?2. Analysis of the cells’ optical and carrier recombination characteristics indicates that the enhanced performance is most likely attributed to a combination of favorable photonic structure and reduced bimolecular recombination losses in WS2-based cells. The achieved PCE is the highest reported to date for organic solar cells comprised of 2D charge transport interlayers and highlights the potential of TMDs as inexpensive HTLs for high-efficiency organic photovoltaics.
关键词： liquid exfoliation,2D transition metal disulfides,nonfullerene organic solar cells,hole transport layers,MoS2,WS2
更新于2025-09-19 17:13:59
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Metal–Organic Framework‐Derived N‐Rich Porous Carbon as an Auxiliary Additive of Hole Transport Layers for Highly Efficient and Long‐Term Stable Perovskite Solar Cells
摘要： As the standard bidopants of hole transport layers (HTLs) in perovskite solar cells (PSCs), bis(tri?uoromethane)sulfonimide lithium salt (Li-TFSI) and 4-tert-butylpyridine not only induce adverse in?uence on the quality of thin ?lms, but also seriously impair the long-term stability of devices. Herein, a metal–organic framework-derived 2D graphitic N-rich porous carbon (NPC) is ?rst introduced into the HTLs as an effective auxiliary additive. The introduction of NPC signi?cantly reduces the aggregation of lithium salts and the formation of HTL defects, optimizing ?lm quality for rapid hole extraction and migration. Furthermore, inherent porosity and hydrophobicity of NPCs are extremely bene?cial to restrict the permeation of Li ions and anode metals, and prevent the moisture from eroding the HTLs and perovskite layers, enhancing the stability of PSCs. As expected, the PSCs with NPC realize a satisfactory ?ll factor of 0.76 and power conversion ef?ciency (PCE) of 18.51%, apparently higher than that of pristine devices (0.70% and 16.47%). In addition, over 85% of the initial PCE for optimized PSCs is maintained after 720 h of exposure to air. Obviously, an innovative strategy for highly ef?cient and long-term stable PSC devices is provided.
关键词： metal–organic frameworks,perovskite solar cells,auxiliary additives,hole transport layers,N-rich porous carbons
更新于2025-09-19 17:13:59
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Carbazole-Based Hole-Transport Materials for High-Efficiency and Stable Perovskite Solar Cells
摘要： As organic–inorganic halide perovskite solar cells (PSCs) near commercialization, stability challenges during real-world conditions, such as elevated temperatures, still need to be addressed. We have previously reported triarylamine-based hole transport layers (HTLs) doped with a triarylamine-based radical cation salt (EHCz-3EtCz/EH44-ox) lead to enhanced PSC stability at elevated temperatures. While it was shown the radical cation dopant did not need to be identical to the HTL matrix, little was known about dopant exchange to realize maximum impact on device-level properties (e.g., increase the low intrinsic conductivity, mobility, hydrophobic properties, synthetic ease and thermal stability). In this paper, we study the impact of dopant exchange among stable, low cost, high glass transition temperature (Tg), and easily synthesized triarylamine-based HTL and radical triarylamine cation salts as dopants. Using EH44-ox as dopant leads to the improved device-level PCE for all HTL matrices assessed. Moreover, increasing the number of ethylhexyl chains from one to two per molecule, and positioning these chains at the periphery rather than the core resulted in improved hydrophobicity. PSCs based on our HTL formulations have similar power conversion efficiency (PCE) as that of PSCs based on commercially available HTLs, while demonstrating greatly improved device-level stability at elevated temperature.
关键词： EtCz-3EHCz,dopant exchange,hole transport layers,Perovskite solar cells,EH44-ox
更新于2025-09-19 17:13:59
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Solutiona??Processable Anode Double Buffer Layers for Inverted Polymer Solar Cells
摘要： Although organic solar cells have surpassed the 17% power conversion efficiency threshold, commercial modules efficiencies are only around 4-5%. One of the reason, is the lack of effective solution processable hole transport materials, that are a key element for the scale up on roll-to-roll printing equipments and the commercial development. In this work, we have developed a class of novel vanadium and molybdenum polyoxometallate salts that, alone or in combination with a traditional poly(ethylene-3,4-dioxytiophene):poly(styrene sulfonate) (PEDOT:PSS) layer, can be employed as anodic buffer layer in inverted polymer solar cells. These materials exhibit work function values around 5.8 eV that match well with HOMO energies of typical polymer donors. They have been tested with different widely used active systems, including PTB7:PC71BM, PV2000:PCBM and PffBT4T:PC71BM. Vanadium and molybdenum polyoxometallate can be deposited from solutions and, contrary to PEDOT:PSS used alone, do not cause a drop of performances compared to evaporated molybdenum oxide (e-MoOx); on the contrary, in the best cases they achieve similar performances to e-MoOx. Slot-die coated PV2000:PCBM solar cells on flexible substrate achieve a remarkable power conversion efficiency of almost 7.6%.
关键词： heteropolyacid salts,soluble buffer layers,hole transport layers,polymer solar cells
更新于2025-09-16 10:30:52