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Enhanced performance of ternary organic solar cells with a wide bandgap acceptor as the third component
摘要： Two n-type organic semiconductor (n-OS) acceptors, C8-SF and Y-MODF, were designed and synthesized for application in organic solar cells (OSCs). C8-SF shows a lower lowest unoccupied molecular orbital (LUMO) energy level and lower bandgap with an absorption edge at 822 nm. Y-MODF possesses a relatively larger bandgap and higher LUMO and lower HOMO (highest occupied molecular orbital) energy levels than C8-SF. With the polymer PM6 as the donor, the OSC with C8-SF as the acceptor delivers a power conversion efficiency (PCE) of 11.59% with a lower open circuit voltage (Voc) of 0.787 V, while the device with Y-MODF as the acceptor exhibits a lower PCE of 8.63% but a higher Voc of 0.984 V benefiting from the higher LUMO of the Y-MODF acceptor. Then, a series of ternary OSCs were fabricated with PM6:C8-SF as the host system and Y-MODF as a third component. The optimal ternary OSCs with 25% Y-MODF incorporated into the acceptor achieve a higher PCE of 13.39%, with an improved Voc of 0.845 V, a Jsc of 20.88 mA cm?2 and a FF of 75.87%. It was found that adding Y-MODF to the PM6:C8-SF binary system suppressed monomolecular recombination and improved the utilization of 450–600 nm range photons. Molecular packing is further optimized with more balanced hole and electron transport, thus resulting in the enhanced Jsc and FF for the ternary OSCs. These results indicate that the addition of a wide bandgap acceptor with a higher LUMO energy level to a binary donor/acceptor system may have potential for Voc and PCE improvement of ternary OSCs.
关键词： ternary OSCs,n-type organic semiconductor,organic solar cells,open circuit voltage,power conversion efficiency
更新于2025-09-16 10:30:52
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A universal approach for optimizing charge extraction in electron transporting layer-free organic solar cells <i>via</i> Lewis base doping
摘要： Although the improvement of power conversion efficiency (PCE) in organic photovoltaic cells (OSC) is due to the development of novel donors and non-fullerene acceptors, state-of-the-art devices commonly utilize charge transporting/extraction interlayers. Here we demonstrate a universal approach based on a series of tetraalkyl ammonium bromide (TXABr) Lewis bases as n-dopants for mediating electron extracting properties in a range of OSCs with non-fullerene or PCBM acceptors. Under optimal conditions, the TXABr-doped devices without electron transporting layers (ETLs) exhibit PCEs comparable to those of the ones based on a conventional device structure containing ETLs. We found that the doping efficiency of acceptors is intimately correlated with the chain length (Lchain) of dopants. In OSCs based on acceptors of ITIC derivatives (IT-4F, ITIC, ITM, and ITCC), similar Lchain-dependent doping efficiency and PCE modification are found, while for OSCs with acceptors bearing different structures in conjugated backbones or side chains, the selection rule of dopants to achieve the best performance enhancement is different. These correlations are explained by the mutual effects of electrostatic interaction in the dopants and steric hindrance between the dopants and acceptors, the latter of which is affected by the compatibility of side chains in the host and dopant. With TXABr doping, (quasi-)ohmic contacts for electrons are realized in these ETL-free devices, leading to expediting the charge sweepout with mitigated interfacial charge recombination. This work offers a promising pathway to realize high efficiency non-fullerene OSCs with simplified device architecture.
关键词： organic solar cells,power conversion efficiency,charge extraction,Lewis base doping,electron transporting layer-free
更新于2025-09-16 10:30:52
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Platinum counter electrodes for dye-sensitized solar cells prepared by one-step dipping process
摘要： When designing counter electrodes (CEs) to enhance the performance of dye-sensitized solar cells (DSSCs), facile routes are important features. Platinum (Pt) metal is one of the most-promising CE designs for DSSCs. Herein, we developed a simple, and cost-effective one-step dipping process for preparing Pt CEs in DSSCs. The Pt CEs were prepared by dipping fluorine-doped tin oxide (FTO) in a 3-mercaptopropyl triethoxysilane (MTS)-Pt suspension. We tested and compared MTS-1-Pt, MTS-10-Pt, and sputtered-Pt as CEs in DSSCs. MTS-1-Pt and MTS-10-Pt refer to samples prepared with 1 and 10 ml of MTS, respectively. DSSCs with MTS-1-Pt CEs exhibited power conversion efficiency (PCE) values as high as 8.28%, which was superior to the DSSCs using MTS-10-Pt as the CEs (1.61%). Additionally, the DSSCs with MTS-1-Pt CE showed mostly similar PCEs compared to those with sputtered-Pt (8.55%) because of the same catalytic activity with iodide. Thus, this modified Pt CE facile process can be used to further enhance the performance of DSSCs.
关键词： one-step dipping process,catalytic activity,power conversion efficiency,Platinum counter electrodes,dye-sensitized solar cells
更新于2025-09-16 10:30:52
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Significantly improving the performance of polymer solar cells by the isomeric ending-group based small molecular acceptors: Insight into the isomerization
摘要： Compared to benzene-fused end-capping groups (EGs), thiophene-fused EGs have some unique characteristics due to the non-centrosymmetric structure of the thiophene ring, which make them easy to form different types of isomers. Here, we develop three isomeric brominated thiophene-fused EGs, which are linked to the IDTT core to acquire three novel isomeric small-molecule acceptors (SMAs) named ITC-2Br, ITC-2Br1, and ITC-2Br2. From ITC-2Br to ITC-2Br1, the change of the bromine substituent group on the thiophene ring has only a minor impact on the physicochemical properties and photovoltaic performance. However, from ITC-2Br to ITC-2Br2, the change in the fused sites on the thiophene leads to dramatically modified absorption, energy levels, and photovoltaic performance. Theoretical simulations provide an in-depth understanding of the absorption and electrochemical differences among the three acceptors. Thanks to the favorable properties, the ITC-2Br2-based polymer solar cells (PSCs) yield a significantly higher power conversion efficiency (PCE) (13.1%) than the devices based on ITC-2Br (10.9%) and ITC-2Br1 (11.9%). From the ITC-2Br-, ITC-2Br1- to the ITC-2Br2-based devices, the JSC and FF exhibit a monotonic increase similar to the trend of PCE, which demonstrates the success of the isomerization strategy, highlighting its future prospects for the development of high-performance SMAs.
关键词： polymer solar cells,power conversion efficiency,isomerization,small-molecule acceptors,end-capping groups
更新于2025-09-16 10:30:52
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Ternary small molecules organic photovoltaics exhibiting 12.84% efficiency
摘要： Small molecules organic photovoltaics (SMPVs) were prepared with DR3TSBDT as donor, narrow band gap material Y6 and broad band gap material PC71BM as acceptor. The Y6 based binary SMPVs exhibits a power conversion efficiency (PCE) of 10.53%, with short-circuit density (JSC) of 21.67 mA cm-2, open circuit voltage (VOC) of 0.879 V and fill factor (FF) of 55.21%. A 12.84% PCE is achieved from the optimized ternary SMPVs with 40 wt% PC71BM in acceptors, which is attributed to the enhanced JSC of 22.19 mA cm-2 and FF of 67.27% resulting from the well-optimized phase separation with PC71BM as morphology regulator. Hollow spherical structure of PC71BM with high electron mobility may connect Y6 molecules to form the more continuous electron transport channels in ternary active layers. Meanwhile, DR3TSBDT molecular arrangement can be markedly adjusted by incorporating PC71BM to form 3D texture structure. The well-optimized phase separation degree and molecular arrangement in ternary active layers can well support the enhanced FFs of ternary SMPVs compared with that of binary SMPVs. Over 21% PCE improvement is achieved by employing ternary strategy with 40 wt% PC71BM in acceptors, the 12.84% PCE should be among the highest values of SMPVs.
关键词： Small molecules organic photovoltaics,Ternary strategy,Morphology regulator,Power conversion efficiency
更新于2025-09-16 10:30:52
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Forming a metal-free oxidatively-coupled agent, bicarbazole, as a defect passivation for HTM and an interfacial layer in a p-i-n perovskite solar cell exhibits nearly 20% efficiency
摘要： In this study we synthesized three simple and inexpensive (34–120 USD/g) 3,3′-bicarbazole–based hole transporting materials (BC-HTMs; NP-BC, NBP-BC and PNP-BC) through a metal-free oxidative coupling, in excellent yields (≥ 95%). These bicarbazoles contain phenylene or biphenylene substituents on the carbazole N atom, with extended π-conjugation achieved through phenylene units at the 6,6′-positions of the bicarbazole. When using NBP-BC as a dopant-free HTM in a p–i–n perovskite solar cell (PSC), we achieved a power conversion efficiency (PCE) of 13.04% under AM 1.5G conditions (100 mW cm–2); this PCE was comparable with that obtained when using PEDOT:PSS as the HTM (12.67%). BC-HTMs showed the large grain size (μm) of perovskite than PEDOT:PSS-based, due to defect passiviation on indium tin oxide (ITO) substrate and good hydrophobicity. Furthermore, we realized highly efficient and stable PSCs when using the p–i–n device structure ITO/NiOx/NP-BC/perovskite/PC61BM/BCP/Ag. The bifacial defect passivation effect of the interfacial layer improved the grain size of the perovskite layer and also enhanced the performance; the best performance of the NiOx/NP-BC device was characterized by a short-circuit current density (Jsc) of 22.38 mA cm–2, an open-circuit voltage (Voc) of 1.09 V, and a fill factor (FF) of 79.9%, corresponding to an overall PCE of almost 20%. This device structure has competitive potential because its performance is comparable with that of the record high efficiency PSCs. Under an Ar atmosphere, the PCE of the NiOx/NP-BC PSC device decayed by only 4.55% after 168 h; it retained 90.80% of its original PCE after 1000 h. A morphological study revealed that the films of the BC-HTMs were indeed smooth and hydrophobic, and that the perovskite films spin-coated upon them were uniform and featured large grains (micrometer scale). Time-resolved photoluminescence (TRPL) spectra of the perovskite films suggested that the hole extraction capabilities of the NiOx/BC-HTMs were better than that of the bare NiOx. The superior film morphologies of the NiOx/BC-HTMs were responsible for the performances of their devices being comparable with those of bare NiOx-based PSCs.
关键词： power conversion efficiency,3,3′-bicarbazole,perovskite solar cells,hole transporting materials,metal-free oxidative coupling,dopant-free
更新于2025-09-16 10:30:52
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Device characteristics and material developments of indoor photovoltaic devices
摘要： Indoor photovoltaics (IPVs), which convert the indoor light energy into direct electricity, have attracted research attention due to their potential use as an excellent amicable solution of sustainable power source to drive low-power-needed sensors for the internet of things (IoT) applications. Our daily life adopts various indoor light sources, such as indirect sunlight, incandescent lamps, halogen lamps, ?uorescent lamps, and LED bulbs, that typically deliver lower light intensity (200–1000 lux) as compared to that of sun light (～100,000 lx). In this review, we ?rstly classi?ed the indoor lights depending on their working mechanism and resulting emission spectrum. Because the indoor light intensities are rather low that may lead to overestimate/underestimate the power conversion e?ciency (PCE) of IPV devices, then, the cautious points for correctly measuring the indoor light intensity as well as the device characteristics are summarized. Several light sources with various light intensities are reported so far, but for lack of common or standard calibration meter that induces a ambiguity in PCE determination, so we suggest/propose to use a universal LED lux meter with NIST-traceable calibration (e.g. Extech LT40-NIST) and also recommended the device results are expressed in maximum power point Pmax along with PCE values. It is generally believed that the materials play key roles on the performance of the IPV devices. Since the indoor light intensity is much weaker as compared to that of outdoor irradiation, the typical inferior photo-stability of organic materials under sunlight may not be as crucial as we considered to harvest indoor light energy, opening a great room for organic IPV material developments. In principle, all materials for outdoor PVs may also be useful for IPVs, but the fundamental material requirement for IPVs which needs su?ciently covering the absorption range between the 350–700 nm with high molar extinction coe?cient should be primarily concerned. In order to get the thorough knowledge of materials for achieving better e?cient IPVs, the reported IPVs were collected and summarized. According to these reports, the materials utilized for IPVs have been classi?ed into two major groups, inorganic and organic materials, then divided them into several sub-classes, including (1) silicon and III-V semiconductor photovoltaics, (2) dye-sensitized photovoltaics, (3) organic photovoltaics, and (4) perovskite-based photovoltaics, depend on their structural nature and device working principle. For every individual class, the structure-property-e?ciency relationship of the materials was analyzed together with the highlights on the best e?ciency material, challenge and perspective. For inorganic IPV materials, III-V semiconductor GaAs-based IPVs performed a very impressive PCE (28%). For dye sensitizers, there are more ?exible strategies to modulate the absorption pro?les of organic materials. A high e?ciency dye-sensitized solar cell (DSSC)-based IPV with a PCE up to 32% has been successfully realized with co-sensitized dyes. For organic solar cell (OSC)-based IPVs, fullerene-based acceptors are advantageous for their well-matching desired absorption range and superior electron transport features. A recent OSC-based IPV with the active layer composed of dithienobenzene-based donor and fullerene acceptor was reported to deliver a PCE of 28%. Among these emerging photovoltaic materials, it is no doubt that perovskites (e.g. CH3NH3PbI3) are superior for solar energy conversion due to the crystallinity for good charge transport, better spectral coverage and the low exciton binding energy. Until very recent, a perovskite-based IPV with a PCE of 35% was reported with good stability by the incorporation of an ionic liquid for e?ectively passivating the surface of the perovskite ?lm, indicating the bright prospect of perovskite for IPV application. Overall, the review on these reports implies the essential criteria of materials suitable for IPVs that may trigger new ideas for developing future champion materials for various devices and the realization of practical IPV applications.
关键词： Organic solar cells,Dye-sensitized solar cells,Silicon and III-V semiconductors,Perovskite materials,Power conversion efficiency,Internet of Things,Organic materials,Indoor photovoltaics
更新于2025-09-16 10:30:52
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Atomic-Level Microstructure of Efficient Formamidinium-Based Perovskite Solar Cells Stabilized by 5-Ammonium Valeric Acid Iodide Revealed by Multi-Nuclear and Two-Dimensional Solid-State NMR
摘要： Chemical doping of inorganic-organic hybrid perovskites is an effective way of improving the performance and operational stability of perovskite solar cells (PSCs). Here we use 5-ammonium valeric acid iodide (AVAI) to chemically stabilize the structure of α-FAPbI3. Using solid-state MAS NMR, we demonstrate the atomic-level interaction between the molecular modulator and the perovskite lattice and propose a structural model of the stabilized three-dimensional structure, further aided by density functional theory (DFT) calculations. We find that one-step deposition of the perovskite in the presence of AVAI produces highly crystalline films with large, micrometer-sized grains and enhanced charge-carrier lifetimes, as probed by transient absorption spectroscopy. As a result, we achieve greatly enhanced solar cell performance for the optimized AVA-based devices with a maximum power conversion efficiency (PCE) of 18.94%. The devices retain 90% of the initial efficiency after 300 h under continuous white light illumination and maximum-power point-tracking measurement.
关键词： power conversion efficiency,density functional theory,perovskite solar cells,chemical doping,solid-state MAS NMR,charge-carrier lifetimes,5-ammonium valeric acid iodide
更新于2025-09-16 10:30:52
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Platinum leaf counter electrodes for dye-sensitized solar cells
摘要： In this study, a platinum (Pt) leaf was introduced as a counter electrode (CE) with thickness of 100 nm in dye-sensitized solar cells (DSCs). Fundamental characteristics were investigated and compared with Pt leaf, Pt plate, and sputtered-Pt as the CEs. The power conversion efficiencies of DSCs with a Pt leaf as the CEs were as high as 4.78%, which is higher to those of DSCs with Pt plate and sputtered-Pt as the CEs (4.11% and 4.40%, respectively). In contrast to other CEs, Pt leaf features a large surface area. This implies that Pt leaf serves as an active CE and can be a good candidate for DSCs.
关键词： dye-sensitized solar cells,platinum leaf,power conversion efficiency,counter electrode
更新于2025-09-16 10:30:52
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Enhanced performance of CdS/CdSe quantum dot-sensitized solar cells by long-persistence phosphors structural layer; é?????è??è?§??????????±??￠???oCdS/CdSeé???-???1???????¤aé?3 è????μ?±?;
摘要： Light absorption plays an important role in improving the power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs). In this study, a multi-long-persistence phosphor (LPP) layer was introduced into the CdS/CdSe QDSSCs via a simple doctor blade method. The LPP layer can simultaneously improve the light harvesting and photo charge transfer in CdS/CdSe QDSSCs. As a result, their short-circuit current and corresponding PCE are effectively enhanced. The PCE can reach up to 5.07%, which is about 24% larger than that of the conventional CdS/CdSe QDSSCs without LPP layer. The solar cells can work in dark for a while due to the long-lasting fluorescence of the LPP layer. This research provides an effective way to improve the PCE of QDSSCs, and finds the possibility for all-weather QDSSCs.
关键词： long-persistence phosphors,quantum dot-sensitized solar cells,power conversion efficiency,all-weather solar cells
更新于2025-09-16 10:30:52