Recently, emerging third-generation photovoltaic technologies have shown rapid progress in device performance; the power conversion efficiencies (PCEs) of organic bulk heterojunction (BHJ) and ...perovskite solar cells (PSCs) are now surpassing 19% and 25%, respectively. Despite this dramatic enhancement, their efficiencies are theoretically limited based on the detailed balance model which accounts for inevitable loss mechanisms under operational conditions. Integrated solar cells, formed by monolithically integrating two photoactive layers of perovskite and BHJ with complementary absorption, provide a promising platform for further improvement in solar cell efficiency. In perovskite/BHJ integrated solar cells (POISCs), high bandgap perovskite offers high open-circuit voltage with minimal losses while low bandgap organic BHJ extends absorption bandwidth by covering the near-infrared region, resulting in additional photocurrent gain. Different from conventional tandem solar cells, integrated solar cells contain merged photoactive layers without the need for complicated recombination layers, which greatly simplifies fabrication processes. In this review, we summarize the recent progress in POISCs, including operational mechanism and structural development, and remaining challenges on the road toward efficient devices.
Despite the recent unprecedented increase in the power conversion efficiencies (PCEs) of small‐area devices (≤0.1 cm2), the PCEs deteriorate drastically for PSCs of larger areas because of the ...incomplete film coverage caused by the dewetting of the hydrophilic perovskite precursor solutions on the hydrophobic organic charge‐transport layers (CTLs). Here, an innovative method of fabricating scalable PSCs on all types of organic CTLs is reported. By introducing an amphiphilic conjugated polyelectrolyte as an interfacial compatibilizer, fabricating uniform perovskite films on large‐area substrates (18.4 cm2) and PSCs with the total active area of 6 cm2 (1 cm2 × 6 unit cells) via a single‐turn solution process is successfully demonstrated. All of the unit cells exhibit highly uniform PCEs of 16.1 ± 0.9% (best PCE of 17%), which is the highest value for printable PSCs with a total active area larger than 1 cm2.
Large‐area planar perovskite solar cells (PSCs) are demonstrated by an innovative method using an amphiphilic conjugated polyelectrolyte as an interfacial compatibilizer between the hydrophobic organic charge‐transport layer and hydrophilic perovskite layer. Highly scalable PSCs with uniform perovskite films on a large‐area substrate (18.4 cm2) and with an active area of 1 cm2 exhibit stabilized power conversion efficiencies of 17%.
Stretchable conductive materials have received great attention owing to their potential for realizing next-generation stretchable electronics. However, the simultaneous achievement of excellent ...mechanical stretchability and high electrical conductivity as well as cost-effective fabrication has been a significant challenge. Here, we report a highly stretchable and highly conducting polymer that was obtained by incorporating an ionic liquid. When 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) was added to an aqueous conducting polymer solution of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it was found that EMIM TCB acts not only as a secondary dopant but also as a plasticizer for PEDOT:PSS, resulting in a high conductivity of >1000 S cm–1 with stable performance at tensile strains up to 50% and even up to 180% in combination with the prestrained substrate technique. Consequently, by exploiting the additional benefits of high transparency and solution-processability of PEDOT:PSS, we were able to fabricate a highly stretchable, semitransparent, and wholly solution-processed alternating current electroluminescent device with unimpaired performance at 50% strain by using PEDOT:PSS/EMIM TCB composite films as both bottom and top electrodes.
The fabrication of organic photovoltaic modules via printing techniques has been the greatest challenge for their commercial manufacture. Current module architecture, which is based on a monolithic ...geometry consisting of serially interconnecting stripe-patterned subcells with finite widths, requires highly sophisticated patterning processes that significantly increase the complexity of printing production lines and cause serious reductions in module efficiency due to so-called aperture loss in series connection regions. Herein we demonstrate an innovative module structure that can simultaneously reduce both patterning processes and aperture loss. By using a charge recombination feature that occurs at contacts between electron- and hole-transport layers, we devise a series connection method that facilitates module fabrication without patterning the charge transport layers. With the successive deposition of component layers using slot-die and doctor-blade printing techniques, we achieve a high module efficiency reaching 7.5% with area of 4.15 cm(2).
The high-resolution, inkjet-printed zinc oxide (ZnO) microdot arrays with suppressed coffee-ring effect was demonstrated by investigating the correlation between drying and solidification processes. ...The internal microfluidic behavior of an ejected droplet and the associated drying process is geometry-dependent, which can be controlled by the temperature and surface energy of the substrate. During evaporation, droplets in contact with a wettable surface exhibit a dominant outward convective flow, resulting in a pronounced coffee-ring effect. In contrast, for droplets with minimal contact area on a substrate with low surface energy, the surface energy gradient along the relatively long thermal conducting path length reinforces the Marangoni flow, which retards the pinning of the contact line, resulting in tiny microdots with suppressed coffee-ring effect. The controlled ZnO microdots exhibit a diameter of approximately 3 μm with a thickness of 50 nm, which is one of the smallest microstructures produced by the inkjet printing method. Additionally, the integration of the ZnO microdot arrays into organic solar cells aimed to alter the light path length, leading to enhanced internal absorption. The P3HT:PCBM, PTB7-Th:PCBM, and PM6:Y6 devices with ZnO microdot arrays exhibit higher power conversion efficiencies of 3.54%, 9.04%, and 15.61% compared to reference devices of 3.38%, 8.85%, and 15.25% respectively.
Efforts to commercialize organic solar cells (OSCs) by developing roll-to-roll compatible modules have encountered challenges in optimizing printing processes to attain laboratory-level performance ...in fully printable OSC architectures. In this study, we present efficient OSC modules fabricated solely through printing methods. We systematically evaluated the impact of processing solvents on the morphology of crucial layers, such as the hole transport, photoactive, and electron transport layers, applied using the doctor blade coating method, with a particular focus on processability. Notably, deposition of charge transport layer using printing techniques is still a challenging task, mainly due to the hydrophobic characteristic of the organic photoactive layer. To overcome this issue, we investigated the solvent effect of a well-studied cathode interlayer, bathocuproine (BCP). We were able to form a uniform thin BCP film (∼10 nm) on a non-fullerene based organic photoactive layer using the doctor bladed coating method. Our results showed that the use of volatile alcohols in the BCP processing required a delicate balance between wettability and vaporization, which contrasted with the results for spin-coated films. These findings provide important insights into improving the efficiency of printing techniques for depositing charge transport layers. The fully printed OSC modules, featuring uniform and continuous BCP layer formation, achieved an impressive power conversion efficiency of 10.8% with a total area of 10.0 cm2 and a geometrical fill factor of 86.5%.
Interface engineering based on amine-containing polyelectrolytes has been proven to be useful for high-performance organic and perovskite solar cells by improving charge collection at the interfaces. ...Here, we demonstrate efficient organic and perovskite solar cells by introducing non-conjugated polyelectrolyte, linear polyethyleneimine (LPEI), as a cathode interfacial layer (CIL). Notably, such a polyelectrolyte contains secondary amine groups in its molecular structure, which could provide chemical stability with most of the state-of-the-art non-fullerene acceptors (NFAs), and concurrently form dipole layer to endow underlying materials with work function tunability. As a result of favorable interfacial contact, organic solar cells with LPEI CIL exhibited a high power conversion efficiency (PCE) of 14.8%. Furthermore, it was found that the LPEI is compatible with conventional metal oxides such as zinc oxide (ZnO) and tin oxide (SnO2) as a bilayer configuration, leading to an increase of PCE from 14.7% to 16% for organic solar cells and from 17.5% to 20% for perovskite solar cells, respectively.
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•Linear polyethyleneimine (LPEI) provides functional amine groups for energy level tunability.•The secondary amine groups of LPEI exhibit enhanced chemical stability.•Both organic and perovskite solar cells with LPEI exhibit enhanced device performance.
The connection performance between cross-laminated timber (CLT) walls and support has the greatest effect on the horizontal shear strength. In this study, the horizontal shear performance of CLT ...walls with reinforced connection systems was evaluated. The reinforcements of metal bracket connections in the CLT connection system was made by attaching glass fiber-based reinforcement to the connection zone of a CLT core lamina. Three types of glass fiber-based reinforcement were used: glass fiber sheet (GS), glass fiber cloth (GT) and fiber cloth plastic (GTS). The horizontal shear strength of the fabricated wall specimens was compared and evaluated through monotonic and cyclic tests. The test results showed that the resistance performance of the reinforced CLT walls to a horizontal load based on a monotonic test did not improve significantly. The residual and yield strengths under the cyclic loading test were 38 and 18% higher, respectively, while the ductility ratio was 38% higher than that of the unreinforced CLT wall. The glass fiber-based reinforcement of the CLT connection showed the possibility of improving the horizontal shear strength performance under a cyclic load, and presented the research direction for the application of real-scale CLT walls.
This study was carried out in order to evaluate the bending creep deflection of glulams and bolted glulams beam-to-beam connection with steel-gusset plates and bolts under changing relative humidity. ...The two types of glulam beams (130 mm in width, 175 mm in thickness, and 3000 mm in length) used in this study were made from domestic larch and composed of seven layers. The gussets were made of 8-mm-thick steel plates. Creep testing was conducted under constant loads in an uncontrolled environment. The test was carried out in a room that was well ventilated through a window. The creep test specimens were loaded for 33,000 hours. A bending creep test for the glulams was conducted through four-point loading. The applied stresses were 20% and 30% of the MOR in the static bending test for the glulam and bolted glulam, respectively. After 33,000 hours, the creep deflection of the glulam at a 20% stress level increased by 39% to 99%, while the creep deflection of the glulam at a 30% stress level increased by 27% to 67%, as compared with instantaneous elastic deflection. The relative creep increased during autumn and winter, and recovered during spring and summer. The relative creep of the bolted glulams was changed abruptly by loading up to 5,000 hours, but stabilized after 5,000 hours, and then gradually increased until 33,000 hours. The relative creep of the bolted glulam increased 2.11 times on average after 33,000 hours.
We developed bulk-heterojunction (BHJ) polymer solar cells (PSCs) by slot-die coating a poly(3-hexylthiophene):fullerene derivative 6,6-phenyl-C61 -butyric acid methyl ester (P3HT:PCBM) composites ...with various solvents, such as chlorobenzene (CB), dichlorobenzene (DCB), or a CB/DCB co-solvent. To understand the effect of solvent on the uniform active layer film coating and charge carrier recombination, we characterized the coated films with UV-visible absorption spectroscopy, and analyzed the measured light intensity dependence of the cells' short-circuit current density (J sub(sc)) and open-circuit voltage (V sub(oc)). The PSC with the active layer that was made with a CB/DCB co-solvent shows better uniform film quality and power conversion efficiency (PCE) due to its relatively small bimolecular and trap-assisted recombination. Finally, we successfully fabricated a uniform large-area PSC module from P3HT:PCBM with a CB/DCB co-solvent system, which shows a PCE of 1.73% under the condition of air mass 1.5.
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