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Applications of atomic layer deposition and chemical vapor deposition for perovskite solar cells
摘要： Metal halide perovskite solar cells (PSCs) have rapidly evolved over the past decade to become a photovoltaic technology on the cusp of commercialization. In the process, numerous fabrication strategies have been explored with the goal of simultaneously optimizing for device efficiency, stability, and scalability. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) have proven to be effective tools for the fabrication of various components of PSCs. This review article examines the application of CVD and ALD for the deposition and modification of charge transport layers, passivation layers, absorber materials, encapsulants, and electrodes. It outlines the use of these vapor deposition techniques in state-of-the-art, multi-junction solar cell devices, and also contains a discussion of the stability of metal halide perovskite materials under CVD and ALD conditions based on in-situ characterization reported in literature. This article concludes with insights into future CVD and ALD research directions that could be undertaken to further aid the deployment of PSCs in emerging solar photovoltaic markets.
关键词： absorber materials,passivation layers,encapsulants,atomic layer deposition,charge transport layers,chemical vapor deposition,perovskite solar cells,electrodes
更新于2025-09-23 15:21:01
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Sa?ˉCl intramolecular interaction: An efficient strategy to improve power conversion efficiency of organic solar cells
摘要： Noncovalent conformational locks (NCLs) including S···N, Se···O, and S···O etc. have been an effective strategy to improve the planarity and rigidity, and charge transport mobility of organic/polymeric semiconductors. Herein, by replacing methyl group (ITMIC) with chlorine (ITCIC) in the π-bridge, the planarity and rigidity of the π-conjugated skeleton was enhanced by introduction of S···Cl NCLs, thus the charge transport mobility was improved accordingly. As a result, PM6:ITCIC based organic solar cells showed impressive PCE of 11.34%, much higher than that based on PM6:ITMIC. This contribution demonstrated a novel kind NCLs (S···Cl) for improving the performance of organic solar cells.
关键词： noncovalent conformational locks,organic solar cells,non-fullerene acceptor,charge transport mobility
更新于2025-09-23 15:21:01
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Alignment of Lyotropic Liquid Crystalline Conjugated Polymers in Floating Films
摘要： Directed alignment of polymer chains plays an indispensable role in charge transport properties. We focus not only on a specific method to induce the alignment but also on the design of a liquid crystalline (LC) conjugated polymer to take advantage of an intrinsic self-assembly characteristic. We synthesized a lyotropic LC conjugated polymer, CP1-P, having o-nitrobenzyl (ONB) esters as photocleavable side chains and adopted a floating film transfer method to induce the polymer chain alignment through a lyotropic LC phase transition. An optimum amount of a high boiling point solvent (1,2-dichlorobenzene) in chloroform turned out to be an important factor to maximize the polymer chain alignment. The hole transport mobility along the polymer chain alignment direction was 13?14 times higher than that in the direction perpendicular to the alignment. In addition, the removal of side chains resulted in the solvent resistivity while maintaining the alignment feature in organic thin-film transistors.
关键词： floating films,liquid crystalline conjugated polymers,photocleavable side chains,polymer chain alignment,charge transport properties
更新于2025-09-23 15:21:01
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Flexible diphenylsulfone versus rigid dibenzothiophene-dioxide as acceptor moieties in donor-acceptor-donor TADF emitters for highly efficient OLEDs
摘要： Flexible versus rigid molecular structures of donor-acceptor-donor type compounds are investigated with respect to efficiency of thermally activated delayed fluorescence (TADF) by theoretical and experimental approaches. Three highly efficient TADF emitters based on flexible diphenylsulfone and rigid dibenzothiophene dioxide as acceptor units and di-tert-butyldimethyldihydroacridine as donor moiety were designed and synthesized. Despite they showed similar singlet-triplet splitting (0.01-0.02 eV) and high photoluminescence quantum yields in appropriate hosts, maximum external quantum efficiencies as different as 24.1 and 15.9/19.4% were obtained for organic light emitting devices based on these emitters with, respectively, flexible and rigid molecular structures. The high efficiency of the light-emitting compounds with the flexible molecular structure could be traced to the bi-configurational nature of the lowest singlet and triplet states resulting in higher spin-orbit coupling than for molecules with rigid structures. All derivatives showed bipolar charge transport character. High device efficiency with electron mobility of 3×10-5 cm2V-1s-1 and hole mobility of 1.3×10-4 cm2V-1s-1 at the electric field of 5×105 Vcm-1 was recorded for the layer of para-disubstituted diphenylsulfone with flexible molecular structure. This TADF emitter showed an excellent performance in the organic light emitting device, exhibiting a maximum current efficiency, power efficiency, and external quantum efficiency of 61.1 cdA-1, 64.0 lmW-1, and 24.1%, respectively.
关键词： Thermally activated delayed fluorescence,diphenylsulfone,di-tert-butyldimethyldihydroacridine,bipolar charge transport,dibenzothiophene dioxide
更新于2025-09-23 15:21:01
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Compositionally graded SnO2/TiO2 bi-layered compounds with dramatically enhanced charge transport efficiency for self-driven water purification applications
摘要： To maximize the advantages of thin-film-based TiO2 photoelectrodes for transparent self-driven photoelectrochemical (PEC) reactions, we artificially designed a compositionally graded bi-layer compounds consisting of SnO2 and TiO2. This structure exhibited a vigorous photocatalytic activity, sufficient photovoltage, and long-term stability. A compositionally graded SnO2/TiO2 interface (G-SnTiO) for improved charge transport efficiency and sufficient photovoltage was derived by a solution process using simultaneous sintering after sol-gel coating the SnO2/TiO2 layers; the structure was verified by various analysis methods, such as transmission electron microscopy, energy dispersive X-ray spectroscopy, and secondary ion mass spectrometry. The high performance from the G-SnTiO structure was attributed to an effective charge separation from the formation of a heterostructure interface with reduced defects, resulting in a sufficient photovoltage for self-driving. To construct self-driven and sustainable overall cells without an external potential and considerable reduction in transparency, two-electrode PEC cells with a G-SnTiO photoanode and Cu2O photocathode were fabricated with a regular hexahedron shape for a color degradation test of methylene-blue-incorporated electrolytes, and exhibited enhanced purification speed and robust durability.
关键词： Charge transport,Photoelectrochemistry,Water oxidation,Compositionally graded structure,Self-driven overall cell
更新于2025-09-23 15:21:01
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Influence of Film Morphology on Transient Photocurrent Pulse Shape in Organic Thin Films: A Monte Carlo Study
摘要： The in?uence of ?lm morphology on the broadening of the time-of-?ight transient photo-current pulse is investigated using Monte Carlo simulation. Simulation of the time-of-?ight transient photo-current pulse shape is carried out for homogeneous and inhomogeneous organic thin ?lms by varying the overall energetic disorder. In homogeneous system, the value of the tail broadening parameter (W) of the photocurrent pulse is found to decrease upon decreasing the energetic disorder, which can be attributed to the variation in the non-thermal ?eld assisted diffusion. Interestingly, in the case of inhomogeneous system, upon decreasing the overall energetic disorder of the system the value of W initially attains a maximum value before it starts decreasing. This observation is explained in terms of the morphology dependent carrier diffusion. This study asserts the importance of the in?uence of the morphology dependent carrier diffusion on the charge transport in disordered systems and the related experimental measurements.
关键词： Polycrystalline organic thin ?lms,Charge transport,Tail broadening,Diffusion,Time of ?ight photoconductivity,Film Morphology
更新于2025-09-23 15:21:01
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Charge-transport layer engineering in perovskite solar cells
摘要： Photovoltaic (PV) technology that directly converts the solar energy into electrical energy, is regarding as one of the most promising utilization technologies of renewable and clean energy sources. Nowadays, developing low-cost and highly efficient PV technology is a hot research topic both for academia and industry. In this context, perovskite solar cells (PSCs) with metal halide perovskites [ABX3, A = CH3NH3+ (MA+), or CH(NH2)2+ (FA+), Cs+; B = Pb2+, Sn2+; X = Cl?, Br?, I?] as light harvesting material, is in the spotlight due to its easy fabrication process and high power conversion efficiency (PCE) [1,2]. To date, the certified PCE has been already pushed up to 25.2% (https://www.nrel.gov/pv/module-efficiency.html), making PSC an auspicious candidate for a new generation of photovoltaics. In future days, how to eliminate the non-essential charge carrier recombination in the device, further push the PCE approaching the Shockley-Queisser theoretical efficiency limit (~35%) and enhance the device stability, will be formidable challenges and the focus in the next stage of research work.
关键词： electron transport layer,hole transport layer,charge-transport layer,perovskite solar cells,power conversion efficiency
更新于2025-09-23 15:19:57
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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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Performance improvement of polymer solar cells with binary additives induced morphology optimization and interface modification simultaneously
摘要： Active layer morphology optimization and electrode buffer layer interface modification are commonly used strategies in improving the performance of polymer solar cells (PSCs). In this study, we prepared PTB7: PC71BM bulk heterojunction PSCs with 1,8-diiodooctane (DIO) and polyethylene glycol (PEG) additives, and studied the influence of binary additives on exciton dissociation, charge transport and charge extraction. DIO facilitates donor/acceptor phase separation for efficient exciton dissociation and charge transport. The migration of PEG from active layer to the PEDOT:PSS layer improves the crystallinity of PTB7, optimizes charge transport pathway, and enhances the conductivity of PEDOT:PSS layer. With the combined advantages of binary additives in active layer morphology optimization and anode buffer layer modification, the device exhibits a high short-circuit current density of 20.03 mA/cm2 and an improved power conversion efficiency. Binary additive provides a promising method to optimize active layer morphology and improve interfacial buffer layer of PSCs simultaneously.
关键词： Charge extraction,Charge transport,Binary additive,Polymer solar cells,Morphology,Interface modification
更新于2025-09-23 15:19:57
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On the Question of the Need for a Built-In Potential in Perovskite Solar Cells
摘要： Perovskite semiconductors as the active materials in efficient solar cells exhibit free carrier diffusion lengths on the order of microns at low illumination fluxes and many hundreds of nanometers under 1 sun conditions. These lengthscales are significantly larger than typical junction thicknesses, and thus the carrier transport and charge collection should be expected to be diffusion controlled. A consensus along these lines is emerging in the field. However, the question as to whether the built-in potential plays any role is still of matter of some conjecture. This important question using phase-sensitive photocurrent measurements and theoretical device simulations based upon the drift-diffusion framework is addressed. In particular, the role of the built-in electric field and charge-selective transport layers in state-of-the-art p–i–n perovskite solar cells comparing experimental findings and simulation predictions is probed. It is found that while charge collection in the junction does not require a drift field per se, a built-in potential is still needed to avoid the formation of reverse electric fields inside the active layer, and to ensure efficient extraction through the charge transport layers.
关键词： perovskite solar cells,charge collection,built-in potential,charge transport layers
更新于2025-09-23 15:19:57