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A novel nematic tri-carbazole as a hole-transport material for solution-processed OLEDs
摘要： Two structural isomers of alkyl-substituted tri-carbazoles were synthesised to study the effect of the substitution pattern on their liquid crystalline behaviour and conductivity and performance in test OLEDs. The isomer with a 2,7-disubstitution pattern in the central carbazole exhibits a monotropic nematic phase, a high conductivity up to 10 Cd A?1 and is suitable as a hole-transport material for solution-processed OLEDs, achieving a high efficiency. The tri-carbazole isomer with a 3,6-substitution pattern, in the central carbazole, does not exhibit observable liquid crystalline behaviour, exhibits conductivity values two orders of magnitude lower than that of its 2,7-disubstituted isomer and performs poorly in OLEDs with the same configuration. Two structural isomers of alkyl-substituted tri-carbazoles A and B exhibit significantly different liquid crystalline behaviour, conductivity and performance in test OLEDs dependent upon their molecular shape.
关键词： nematic mesophases,hole transport materials,Tri-carbazole liquid crystalline isomers,solution-processed OLED
更新于2025-09-23 15:21:01
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Pyridine Bridging Diphenylamine-Carbazole with Linking Topology as Rational Hole Transporter for Perovskite Solar Cells Fabrication
摘要： Developing cost-effective and rational hole transporting materials is critical for fabricating high-performance perovskite solar cells (PSCs) and to promote their commercial endeavor. We have designed and developed pyridine (core) bridging diphenylamine-substituted carbazole (arm) small molecules, named as 2,6PyDANCBZ and 3,5PyDANCBZ. The linking topology of core and arm on their photophysical, thermal, semiconducting and photovoltaic properties were probed systematically. We found that the 2,6PyDANCBZ shows higher mobility and conductivity along with uniform film-forming ability as compared to 3,5PyDANCBZ. The PSCs fabricated with 2,6PyDANCBZ supersede the performance delivered by Spiro-OMeTAD, and importantly also gave improved long-term stability. Our findings put forward small molecules based on core-arm linking topology for cost-effective hole selective layers designing.
关键词： hole transport materials,charge transport,electro-optical properties,perovskite solar cells,Carbazole
更新于2025-09-23 15:19:57
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Liquid State and Zombie Dye Sensitized Solar Cells with Copper Bipyridine Complexes Functionalized with Alkoxy Groups
摘要： Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolyte or as solid state hole transport materials (HTMs). The solid state devices, employing copper complex HTMs can be simply obtained by solvent evaporation in liquid state devices. During this evolution, the copper complex molecules present in the electrolyte solvent slowly aggregate in the pores of the TiO2 film and they also close the gap between the TiO2 film and counter electrode. However, the crystallization of the HTM infiltrated in the mesoscopic TiO2 pores can lead to low photovoltaic performance. In order to prevent this problem, we designed two copper redox mediators [Cu(beto)2]1+ (beto=4,4’-diethoxy-6.6’-dimethyl-2,2’-bipyridine) and [Cu(beto2Ox)2]1+ (beto2Ox=4,4’-bis(2-methoxyethoxy)-6,6’-dimethyl-2,2’-bipyridine) with extended side chains. Firstly, we studied these complexes in liquid state devices in reference to the [Cu(tmby)2]2+/1+ complex (tmby = 4,4?,6,6?- tetramethyl-2,2?-bipyridine). The solar-to-electrical power conversion efficiencies for liquid state devices, were over 10% for all of the complexes by using the organic Y123 dye under 1000 Wm-2 AM1.5G illumination. However, solid state devices showed significantly diminished charge transport properties and short circuit current density values even though the crystallization is reduced.
关键词： Hole transport materials,Dye sensitized solar cells,Crystallization,Photovoltaic performance,Copper redox mediators
更新于2025-09-23 15:19:57
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Phenothiazine-Based Hole Transport Materials for Perovskite Solar Cells
摘要： The promising photovoltaic solar cells based on the perovskite light-harvesting materials have attracted researchers with their outstanding power conversion efficiencies (over 23% certified). The perovskite work has geared up in just under a decade and is competing with well-established semiconductor technologies such as silicon (Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). To commercialize the perovskite solar cells, their stability is the major concern. To address the stability issue, several factors need to be taken into account, and one of them is developing stable hole transport materials (HTMs), which are the essential building blocks. In this mini-review, we will discuss the important features of the HTMs, such as design and development of phenothiazine-based HTMs. Since phenothiazine is a low cost and stable molecule compared to the spiro-OMeTAD, it can be modified further via molecular engineering.
关键词： hole transport materials,phenothiazine,power conversion efficiencies,stability,perovskite solar cells
更新于2025-09-23 15:19:57
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Enhanced photovoltaic performance and stability of perovskite solar cells by interface engineering with poly(4-vinylpyridine) and Cu2ZnSnS4&CNT
摘要： Organic-inorganic perovskite solar cells (PSCs) are emerging candidates for next generation photovoltaic devices. In the last decade, PSCs have depicted a rapid development in device performance, meanwhile, the issue of utilizing low-cost, non-toxic materials with chemical stability as well as long term device stabilities are still lacking. To address these issues, an inexpensive, eco-friendly, and environmentally stable nanostructure of the quaternary chalcogenide Cu2ZnSnS4 (CZTS) as an inorganic hole transport material (HTM) has been investigated. Moreover, simultaneously two strategies has been employed to optimize the photovoltaic parameters. First, an interlayer of poly(4-vinylpyridine) (PVP) has been applied between the perovskite and the hole transport layer (HTL). Second, single-walled carbon nanotubes (CNTs) is incorporated into the CZTS HTL. While, the latter only result in higher short circuit current density (Jsc) from 18.3 to 20 mA cm?2, by using both of the strategies an increase in open circuit voltage (Voc) from 0.98 to 1.05 V as well as Jsc from 18.3 to 20.5 mA cm?2 has been observed. The power conversion efficiency (PCE) of the record device reached to 15.2%, fill factor (FF) increased up to 70% and also demonstrated low hysteresis of 2.3%. The formation of hydrophobic CNT webs among the sphere-like CZTS nanostructures and the presence of the PVP polymeric interlayer results in highly stable devices, which retained more than 98% of the initial PCE at room temperature and 40–45% humidity after 30 days. Thus, our results show that the combination of PVP interlayer and CZTS&CNT HTL offer an opportunity for the scalability of PSCs.
关键词： Cu2ZnSnS4,Inorganic hole transport materials,Stability,Carbon nanotubes,Poly(4-vinylpyridine)
更新于2025-09-23 15:19:57
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Synthesis and Characterization of Spinel Cobaltite (Co3O4) Thin Films for Function as Hole Transport Materials in Organometallic Halide Perovskite Solar Cells
摘要： Conventional inorganic p-type conductive oxides, e.g. NiO, CuOX, and CuCrOX, can serve as low-cost and efficient hole transport materials for wide bandgap organolead halide perovskites [e.g. MAPbI3], but low bandgap Sn-rich organometallic perovskites fail for (FASnI3)0.6(MAPbI3)0.4], where MA = (CH3NH3) and FA = (HC(NH2)2). In this work, we explore spinel Co3O4 based p-type conductive oxides as hole transport materials in organometallic halide MAPbI3 and (FASnI3)0.6(MAPbI3)0.4 perovskite solar cells. We examine the structural, crystalline, optical, electrical, photoelectrochemical, and surface chemistry properties of spin coated Co3O4 films without and with lithium doping. We find that lithium doping improves hole mobilities as well as film optical transparency and causes a lithium enriched overlayer (e.g. LiCoO2) forming at Co3O4 film surface. As a result, lithium doping can maximise the hole transport properties of Co3O4 in our inverted planar perovskite solar cells, achieving about 14% and 7% light-to-electricity power conversion efficiencies (PCEs) for perovskite halides MAPbI3 and (FASnI3)0.6(MAPbI3)0.4, respectively. This work underscores that cobaltite spinels hold promise in application as working HTLs for all kinds of organometallic halide perovskites.
关键词： cobaltite spinels,hole transport materials,doping,Co3O4,perovskite solar cells
更新于2025-09-23 15:19:57
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Dopant-free X-shaped D-A type hole-transporting materials for p-i-n perovskite solar cells
摘要： Azomethine compounds are accessible for palladium-free routes, paving a way for developing highly efficient and eco-friendly hole-transporting materials. This study reports three organic dopant-free X-shaped molecules (named D31, D32, and D33) were systematically designed, synthesized and characterized for fabricating p-i-n perovskite solar cells. The X-shaped design is based on a benzene core unit with four arms attached. Two of them are triphenylamines and two are azomethine bridges connected to functionalized phenyl rings (-H, -OCH3, -CN). These materials show suitable energy levels with respect to that of CH3NH3PbI3 perovskite. Based on this design, it is found that the hydrophobic nature of the three new compounds not only favors the formation of large grained and dense perovskite films but also improves stability of the devices. More encouragingly, the cyano-substituted D33 with donor-acceptor (D-A) type structure exhibit the superiority of high hole mobility and good film-forming property. The optimized unencapsulated device based on D33 in ambient environment exhibit 17.85% efficiency and retained 70% of the initial PCE after 400 hours.
关键词： perovskite solar cells,azomethine,dopant-free,hole-transport materials,donor-acceptor
更新于2025-09-19 17:13:59
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Effect of double bond conjugation on hole mobility of thiophene-based hole transport materials in perovskite solar cells
摘要： It is of great significance to fully explore the relationship between π-bridge size and intermolecular packing for improving the hole mobility of hole transport materials in perovskite solar cells. We performed the density functional theory (DFT) computations of a series of Z26 derivatives (Z26-2, Z26-3, and Z26-4) and investigated the effect of the size of π-bridge and intermolecular packing on hole mobility of hole transport materials. The calculated results show that Z26-2 (7.7 ? 10?4 cm2 V?1 s?1) and Z26-3 (1.3 ? 10?3 cm2 V?1 s?1) have larger hole mobility than Z26 (5.60 ? 10?4 cm2 V?1 s?1) due to their appropriate conjugated length leading to effective face to face packing. The smallest hole mobility of Z26-4 (4.20 ? 10?5 cm2 V?1 s?1) is attributed to its overlong conjugation with four double bonds on each side, which produces a long centroid-to-centroid distance and small electronic coupling. The present theoretical study on the relationship between the size of π-bridge and intermolecular packing provides insight for the future design of thiophene-based hole transport materials.
关键词： Intermolecular packing,Hole transport materials,Density functional theory,Perovskite solar cells,π-bridge size
更新于2025-09-19 17:13:59
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Doping Strategy for Efficient and Stable Triple Cation Hybrid Perovskite Solar Cells and Module Based on Poly(3‐hexylthiophene) Hole Transport Layer
摘要： As the hole transport layer (HTL) for perovskite solar cells (PSCs), poly(3-hexylthiophene) (P3HT) has been attracting great interest due to its low-cost, thermal stability, oxygen impermeability, and strong hydrophobicity. In this work, a new doping strategy is developed for P3HT as the HTL in triple-cation/double-halide ((FA1?x?yMAxCsy)Pb(I1?xBrx)3) mesoscopic PSCs. Photovoltaic performance and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP, and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm2 active area, 16.29% on 1 cm2 active area, and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate the positive effect of a cobalt dopant on the band structure of perovskite/P3HT interfaces leading to improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 h in atmospheric conditions (relative humidity ≈ 60%, r.t.), whereas encapsulated devices show more than >500 h at 85 °C thermal stability (>80%) and 100 h stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.
关键词： perovskite interfaces,light soaking,photovoltaic module,polymeric hole transport materials,thermal stability
更新于2025-09-19 17:13:59
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[IEEE 2019 TEQIP III Sponsored International Conference on Microwave Integrated Circuits, Photonics and Wireless Networks (IMICPW) - Tiruchirappalli, India (2019.5.22-2019.5.24)] 2019 TEQIP III Sponsored International Conference on Microwave Integrated Circuits, Photonics and Wireless Networks (IMICPW) - A Novel Perovskite Solar Cell with ZnO-Cu <sub/>2</sub> O as Electron Transport Material-Hole Transport Material
摘要： Perovskite solar cells have gained remarkable position among the emerging photovoltaic technologies, owing to their increased power conversion efficiency exceeding 20%. The development of various electron transport materials (ETM), perovskite absorbers, hole transport materials (HTM) have contributed well in the efficiency enhancement and stability improvement. One of the major development is the use of ZnO as ETM that replaces TiO2. ZnO has material properties similar to that of TiO2 but possesses improved electron mobility. Moreover, ZnO fabrication methods are easier and of low cost. Cuprous oxide (Cu2O), an earth abundant inorganic p-type material, is recently investigated as a best hole transport material that can replace Spiro-OMeTAD. In this paper, the performance of a planar CH3NH3PbI3 based solar cell using ZnO as ETM and Cu2O as HTM is evaluated using SCAPS 1D software. The combination of ZnO ETM and Cu2O HTM improves the charge transport and reduces the cost. The overall conversion efficiency obtained for the proposed ZnO ? Cu2O perovskite solar cell using CH3NH3PbI3 by SCAPS simulation is 22.77%. The performance of CH3NH3PbI3 based solar cells with ZnO as ETM and with various hole transport materials such as spiro-OMeTAD, CuI, CuSCN and NiO are evaluated and compared with the proposed structure using SCAPS software. The result indicates that ZnO ? Cu2O as ETM-HTM pair is a reliable configuration for CH3NH3PbI3 based solar cell.
关键词： Perovskite,Electron transport materials,Hole transport materials,SCAPS 1D software
更新于2025-09-16 10:30:52