Performance Of Organic Solar Cells Research Articles

Ethanol Processable Inorganic‐Organic Hybrid Hole Transporting Layers Enabled 20.12 % Efficiency Organic Solar Cells

AbstractIn this study, a high‐performance inorganic‐organic hybrid hole transporting layer (HTL) was developed using ethanol‐soluble alkoxide precursors and a self‐assembled monolayer (SAM). Three metal oxides‐vanadium oxide (VOx), niobium oxide (Nb2O5), and tantalum oxide (Ta2O5)‐were synthesized through successive low‐temperature (100 °C) thermal annealing (TA) and UV‐ozone (UVO) treatments of their respective precursors: vanadium oxytriethoxide (EtO−V), niobium ethoxide (EtO−Nb), and tantalum ethoxide (EtO−Ta). Among these, the Nb2O5 film exhibited excellent transmittance, a high work function, and good conductivity, along with a more compact and uniform structure featuring fewer interfacial defects, which facilitated efficient charge extraction and transport. Furthermore, the deposition of a SAM of (2‐(9H‐carbazol‐9‐yl)ethyl)phosphonic acid (2PACz) on top of Nb2O5 further passivated defects, enhancing interfacial contact with the photoactive layer. The resulting inorganic‐organic hybrid HTL of Nb2O5/2PACz demonstrated excellent compatibility with various photoactive blends, achieving impressive power conversion efficiencies of 19.44 %, 19.18 %, and 20.12 % for the PM6:L8‐BO, PM6:BTP‐eC9, and D18:BTP‐eC9 based organic solar cells, respectively. 20.12 % is the best performance for bulk heterojunction organic solar cells with binary components as the photoactive layer.

A Critical Review on Various Buffer Layers used to Enhance the Photovoltaic Performance of Organic Solar Cells

Abstract: Due to the high need for sustainable energy sources, there has been a tremendous increase in SC (solar cell) production and research in recent years. Despite the fact that inorganic SC has led the SC consumer market due to its exceptional efficiency, its expensive and difficult manufacture method makes it unaffordable. Hence alternative technology for SC has been explored by researchers to overcome the draw backs of inorganic SC fabrication. OSC (organic solar cell) alternatively known as polymer SC has the advantage of having lightweight, low production cost, and simple device structure. During the last few years, significant attention has been given in order to overcome the material and technological barriers in OSC devices to make them commercially viable. Buffer layers play a significant part in improving the power conversion efficiencies in OSCs, thus it is necessary to comprehend the underlying microscopic mechanisms that underlie the advancements in order to support the current qualitative knowledge. In this review article, we have studied extensively the impact of different BLs (buffer-layer) in enhancing the PCE (power conversion efficiency) and absorption capabilities of OSCs.

Enhancing Indoor Photovoltaic Performance of Inverted Type Organic Solar Cell by Controlling Photoactive Layer Solution Concentration

With the development of various low-power indoor electronic devices, indoor photovoltaics, particularly organic solar cells (OSCs) have attracted a lot of interest in recent years. Increasing the light absorption and suppressing the leakage current are pivotal to improve the indoor photovoltaic performance of OSCs. In this study, the carbon quantum dots (CQDs)-incorporated photoactive layer solution concentration was varied to improve the photovoltaic performance under 1-sun and indoor white LED illumination. The photoactive layer was composed of (6,6)-phenyl-C61-butyric acid methyl ester) (PCBM) as the acceptor and poly(3-hexylthiophene) (P3HT) as the donor. The ZnO electron transport layer was deposited on fluorine-doped tin oxide (FTO)-coated glass substrates using a spin coating technique. The photoactive layers with different solution concentrations were spin coated on top of the ZnO layer. For device completion, silver anode was thermally evaporated. It is interesting to find that the optimum solution concentration obtained under white LED illumination is larger than that under 1-sun illumination. The maximum power conversion efficiency (PCE) of 0.95% was obtained under 1-sun illumination for device with the solution concentration of 36 mg/mL, whereas, under white LED illumination, the highest PCE of 3.59% was obtained for the device with solution concentration of 48 mg/mL.The discrepancy is ascribed to the higher light absorption of thicker photoactive layer and less significant charge recombination loss under weak light intensity. This study highlights the importance of using different optimization strategies to improve the photovoltaic performance of OSCs for outdoor and indoor applications.

Insulator-donor electron wavefunction coupling in pseudo-bilayer organic solar cells achieving a certificated efficiency of 19.18%

Abstract The incorporation of polymeric insulators has led to notable achievements in the field of organic semiconductors. By altering the blending concentration, polymeric insulators exhibit extensive capabilities in regulating molecular configuration, film crystallinity, and mitigation of defect states. However, current research suggests that the improvement in such physical properties is primarily attributed to the enhancement of thin film morphology, an outcome that seems to be an inevitable consequence of incorporating insulators. Herein, we report a general and completely new effect of polymeric insulators in organic semiconductors: the insulator-donor electron wavefunction coupling effect. Such insulators can couple with donor polymers to reduce the energy barrier level and facilitate the intramolecular electron transport. Besides the morphological effects, we observed that this coupling effect is another mechanism that can significantly enhance the electron mobility (up to 100 times) through the incorporation of polymeric insulators in a series of donor systems. With this effect, we proposed a polymeric insulator blending approach to fabricate state-of-the-art pseudo-bilayer organic solar cells, and the PM6/L8-BO device exhibits a high efficiency of 19.50% (certificated 19.18%) with the improved interfacial electron transport property. This work not only offers a novel perspective on the quantum effect of polymeric insulators in organic semiconductors, but also presents a simple yet effective method for enhancing the performance of organic solar cells.

Regulating Electron‐Phonon Coupling by Solid Additive for Efficient Organic Solar Cells

AbstractStrong electron‐phonon coupling can hinder exciton transport and induce undesirable non‐radiative recombination, resulting in a shortened exciton diffusion distance and constrained exciton dissociation in organic solar cells (OSCs). Therefore, suppressing electron‐phonon coupling is crucially important for achieveing high‐performance OSCs. Here, we employ the solid additive to regulating electron‐phonon coupling in OSCs. The planar configuration of SA1 confers a significant advantage in suppressing lattice vibrations in the active layers, reducing the scattering of excitons by phonons. Consequently, a slow but sustained hole transfer process is identified in the SA1‐assisted film, indicating an enhancement in hole transfer efficiency. Prolonged exciton diffusion length and exciton lifetime are achieved in the blend film processed with SA1, attributed to a low non‐radiative recombination rate and low energetic disorder for charge carrier transport. As a result, a high efficiency of 20 % was achieved for ternary device with a remarkable short‐circuit current. This work highlights the important role of suppressing electron‐phonon coupling in improving the photovoltaic performance of OSCs.

Thienyltriazine Triamides: Thickness Insensitive Interlayer Materials Featuring Fine-Tuned Optoelectronic and Aggregation Characters for Efficient Organic Solar Cells.

A novel class of thienyltriazine triamides (TTTAs) was facile synthesized and firstly used as cathode interlayers (CILs) for organic solar cells (OSCs). By utilizing different aromatic arms and pendant polar groups, their optoelectronic properties and aggregation behaviors were effectively modulated. The combination of thienyltriazine (TT) core, naphthylamide arm and imidazole pendant group endows TT-N-M with suitable energy levels, intensified work function tunability, higher conductivity, and well-balanced crystallinity and film-forming ability, boosting both the performance and stability of OSCs significantly. Remarkably, the solar cell efficiency remains stable at around 90 % of the optimal efficiency even as the interlayer thickness varied from 5 to 95 nm, demonstrating its insensitivity to thickness. Moreover, TT-N-M exhibits compatibility with various active layer systems, achieving a maximum efficiency of 19.60 % for single-junction solar cell. Its exceptional tolerance to thickness fluctuations and performance establishes a new benchmark for multi-armed CIL-based OSCs, also positioning them among the most high-performing CIL materials documented thus far. This work not only broadens the scope of CIL materials for OSCs but also offers deep insights into design strategies and structure-properties relationships, being beneficial for the future development of more efficient CIL materials for organic optoelectronic applications.

Enhancing stability and performance of pseudo-planar heterojunction organic solar cells using a hindered phenolic antioxidant with over 19% efficiency

Enhancing stability and performance of pseudo-planar heterojunction organic solar cells using a hindered phenolic antioxidant with over 19% efficiency

Polymer Based on Asymmetrically Halogenated Benzotriazole Enables High Performance Organic Solar Cells Prepared in Nonhalogenated Solvent.

Halogenation on the A unit of the D-π-A-type polymer donor has been proven as an effective strategy to improve the performance of organic solar cells (OSCs). Compared with fluorination, chlorination usually increases the open-circuit voltage because of the downward shift of energy levels, but decreases the charge transport ability due to the large steric hindrance of the chlorine atom. We reported herein a method to balance the energy loss and charge transport through asymmetric halogenation on the benzotriazole (BTA) unit of the polymer. The designed PE3-FCl based on the BTA unit containing fluorine and chlorine atoms rendered the highest power conversion efficiency (PCE) of 17.83% when eC9-2Cl-γ and o-xylene were used as the electron acceptor and solvent, respectively. The performance is obviously higher than that of the polymer PE3 containing a difluorinated BTA unit (16.65%) and polymer PE3-2Cl with dichlorinated BTA (14.65%) due to the manipulated morphology by preaggregation, improved and more balanced charge carrier transport, and reduced recombination loss. Notably, this PCE is a breakthrough for the BTA-based polymers processed by nonhalogenated solvent. This work gives deep insight into the asymmetric halogenation of polymer donors for high-performance green solvent-processed OSCs.

Achieving High Doping Density in pH-neutral Conjugated Polyelectrolyte Toward Effective Hole-Transporting Materials for Organic Solar Cells.

The lack of effective and non-corrosive hole-transporting layer (HTL) materials has remained a long-standing issue that severely restricts the performance of organic solar cells (OSCs). Most pH-neutral conjugated polyelectrolytes (CPEs) exhibit inferior performance to the acid-doped HTL materials due to their low doping density. In this study, a series of pH-neutral CPEs is designed and synthesized with high doping density as HTL materials. Through an elaborate synthetic route, two sulfonate-terminating alkoxyl side chains can be introduced into thiophene, by which the electron-rich, highly soluble, and chemically stable thiophene monomer is synthesized to enable the subsequent polymerization. The CPE PTT-F exhibit a remarkable self-doping property with an enhanced doping density from 2.01 × 1017 to 7.02 × 1018 cm-3. The high work function and the increased doping density of PTT-F-based HTL decrease the depletion region width from 38.4 to 8.1nm at the anode interface, which minimized the energy loss in hole transport. Consequently, a binary OSC modified by PTT-F-based HTL achieve a high PCE of 18.8%. To the best of the knowledge, this is the highest PCE for OSC employing CPE-based HTL. The results from this work demonstrate an encouraging achievement of realizing exceptional hole collection ability in pH-neutral CPEs.

“Like dissolves like” enables the synergy of fluorinated additive and fluorous solvent soaking for high-performance organic solar cells

The pre-treatment and post-treatment of organic solar cells (OSCs) are two important device engineering processes that are closely associated with photovoltaic performance. Yet these two stages are independently developed to optimize the morphology and then improve the device performance, while their synergy is believed to be more productive. In this study, the fluorinated additive and fluorous solvent soaking (FSS) are simultaneously employed in OSCs, and the “like dissolves like” concept drives their synergetic role on the morphology optimization. The fluorinated additive 1,8-diiodoperfluorooctane (FDIO) could selectively enhance the packing order and crystallinity of the acceptor through forming the fluorine-induced interactions. Moreover, fluorous solvent could penetrate into the blend film and then remove the residue FDIO while further optimizing the morphology by enhancing molecular packing. By employing the synergy of FDIO additive and FSS treatment (40 °C for 30 s), a champion power conversion efficiency (PCE) of 18.64 % with the simultaneous improvements of photovoltaic parameters is achieved. This study provides a synergetic strategy by employing fluorinated additive and fluorous solvent to tune film morphology in the film-formation and post-treatment processes, respectively, consequently advancing the photovoltaic performance of OSCs.

Physics-Informed Machine Learning with Data-Driven Equations for Predicting Organic Solar Cell Performance.

Organic solar cells (OSCs) have emerged as a promising solution in pursuing sustainable energy. This study presents a comprehensive approach to advancing OSC development by integrating data-driven equations from quantum mechanical (QM) descriptors with physics-informed machine learning (PIML) models. We circumvent traditional experimental limitations through high-throughput QM calculations, prioritizing transparent and interpretable models. Using the SISSO++ method, we identified key descriptors that effectively map the relationships between input variables and photovoltaic performance metrics. Our innovative predictive models, derived from SISSO outputs, excel in forecasting critical OSC parameters such as short-circuit current (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCEmax), achieving high accuracy even with limited data sets. To validate our models' practical utility, we applied the PIML framework to a newly compiled data set of OSC devices, demonstrating their versatility and capability in pinpointing high-performance materials. This research underscores the strong predictive power of our models, bridging the gap between experimental results and theoretical predictions and making significant contributions to the advancement of sustainable energy technologies.

Achieving 19.72% Efficiency in Ternary Organic Solar Cells through Electrostatic Potential‐Driven Morphology Control

AbstractThe ternary strategy has proven effective in enhancing the performance of organic solar cells (OSCs), yet identifying the optimal third component remains a challenge due to the lack of theoretical frameworks for predicting its impact based on molecular structure. This study addresses this challenge by proposing quantitative parameters derived from molecular surface electrostatic potential (ESP) as criteria for selecting ternary components. The asymmetric acceptor BTP‐OS, which exhibits a lower total average ESP and larger molecular polarization index relative to the host acceptor, is introduced into the PM6:L8‐BO system. This incorporation led to weakened ESP‐induced intermolecular interactions and reduce miscibility with donor polymer, resulting in an optimized multi‐scale morphology of the ternary blend. Consequently, the ternary device achieved an efficiency of 19.72%, one of the highest values for PM6:L8‐BO‐based ternary devices, with enhanced exciton dissociation and charge collection, lower energy disorder, and minimized non‐radiative energy losses. Comparable efficiency improvements are also verified in PM6:BTP‐eC9 and D18:N3 systems, demonstrating the broad applicability of the proposed approach. This study not only provides a practical and effective principle for selecting ternary components but also establishes a broader framework for optimizing ternary OSCs, potentially advancing the development of more efficient OSCs across diverse material systems.

Ethanol Processable Inorganic-Organic Hybrid Hole Transporting Layers Enabled 20.12 % Efficiency Organic Solar Cells.

In this study, a high-performance inorganic-organic hybrid hole transporting layer (HTL) was developed using ethanol-soluble alkoxide precursors and a self-assembled monolayer (SAM). Three metal oxides-vanadium oxide (VOx), niobium oxide (Nb2O5), and tantalum oxide (Ta2O5)-were synthesized through successive low-temperature (100 °C) thermal annealing (TA) and UV-ozone (UVO) treatments of their respective precursors: vanadium oxytriethoxide (EtO-V), niobium ethoxide (EtO-Nb), and tantalum ethoxide (EtO-Ta). Among these, the Nb2O5 film exhibited excellent transmittance, a high work function, and good conductivity, along with a more compact and uniform structure featuring fewer interfacial defects, which facilitated efficient charge extraction and transport. Furthermore, the deposition of a SAM of (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) on top of Nb2O5 further passivated defects, enhancing interfacial contact with the photoactive layer. The resulting inorganic-organic hybrid HTL of Nb2O5/2PACz demonstrated excellent compatibility with various photoactive blends, achieving impressive power conversion efficiencies of 19.44 %, 19.18 %, and 20.12 % for the PM6:L8-BO, PM6:BTP-eC9, and D18:BTP-eC9 based organic solar cells, respectively. 20.12 % is the best performance for bulk heterojunction organic solar cells with binary components as the photoactive layer.

Gradual Optimization of Molecular Aggregation and Stacking Enables Over 19% Efficiency in Binary Organic Solar Cells.

Volatile solid additive is an effective and simple strategy for morphology control in organic solar cells (OSCs). The development of environmentally friendly new additives which can also be easily removed without high-temperature thermal annealing treatment is currently a trend, and the working mechanism needs to be further studied. Herein, a highly volatile and non-halogenated solid additive 1-benzothiophene (BBT) is reported to regulate molecular aggregation and stacking of active layer components. According to the film-forming kinetics process, a momentary intermediate phase is formed during spin-coating, which slows down the film-forming process and leads to more ordered molecular stacking in the solid film after introducing solid additive BBT. Subsequently, after solvent vapor annealing (SVA) further treatment, the resultant blend films exhibit a tighter and more ordered molecular stacking. Consequently, the synergistic effect of solid additive BBT and SVA treatment can effectively control morphology of active layer and improve carrier transport characteristics, thereby enhancing the performance of OSCs. Finally, in D18-Cl:N3 system, an impressive power conversion efficiency of 19.53% is achieved. The work demonstrates that the combination of highly volatile solid additives and SVA treatment is an effective morphology control strategy, guiding the development of efficient OSCs.

Enhancing photovoltaic performance of organic solar cells by embedding plasmonic Ag nanocuboid array in the active layer

Enhancing photovoltaic performance of organic solar cells by embedding plasmonic Ag nanocuboid array in the active layer

Endgroup engineering of the third component for high-efficiency ternary organic solar cells

In this study, we carefully designed and synthesized three A-D-A type molecules, namely YF-C8-CN, YF-C8-S, and YF-C8-O. These molecules feature a 2,2′-bithiophene core, which bears two 2,4,6-tripropylbenzene steric hindrance groups, as the central electron-donating unit, and utilize rhodanine (Rh), thiazolidinedione, and dicyanoyl-modified benzotriazole (BTA) respectively as the electron acceptor unit (A-unit). We investigated their impact as the third component on the performance of ternary organic solar cells (OSCs). Our studies indicate that YF-C8-S, with rhodanine terminal groups, exhibits complementary absorption characteristics and cascaded energy levels when combined with the host binary system (D18:eC9-4F). Compared to YF-C8-CN and YF-C8-O, ternary OSCs based on YF-C8-S demonstrate significantly higher exciton diffusion and charge transport efficiency, favorably impacting the short-circuit current density (JSC) and fill factor (FF) of the OSCs. Furthermore, devices based on YF-C8-S exhibit reduced non-radiative energy loss, contributing to an enhanced open-circuit voltage (VOC). Consequently, ternary OSCs based on YF-C8-S achieve a remarkable efficiency of 19.12%, positioning it among the highest reported values. This comprehensive research on the third component of the YF-C8 series underscores their significant potential for fabricating high-performance ternary OSCs.

Constructing Multiscale Fibrous Morphology to Achieve 20% Efficiency Organic Solar Cells by Mixing High and Low Molecular Weight D18.

This study underscores the significance of precisely manipulating the morphology of the active layer in organic solar cells (OSCs). By blending polymer donors of D18 with varying molecular weights, a multiscale interpenetrating fiber network structure within the active layer is successfully created. The introduction of 10% low molecular weight D18 (LW-D18) into high molecular weight D18 (HW-D18) produces MIX-D18, which exhibits an extended exciton diffusion distance and orderly molecular stacking. Devices utilizing MIX-D18 demonstrate superior electron and hole transport, improves exciton dissociation, enhances charge collection efficiency, and reduces trap-assisted recombination compared to the other two materials. Through the use of the nonfullerene acceptor L8-BO, a remarkable power conversion efficiency (PCE) of 20.0% is achieved. This methodology, which integrates the favorable attributes of high and low molecular weight polymers, opens a new avenue for enhancing the performance of OSCs.

Magnetic Nanocomposite Modified Hybrid Hole-Transport Layer for Constructing Organic Solar Cells with High Efficiencies.

An interface modification layer holds paramount significance in reducing interface carrier recombination and improving the ohmic contact between the active layer and the electrode in organic solar cells (OSCs). Modifying or doping the widely used hole-transport layer (HTL) PEDOT:PSS to adjust the work function, conductivity, and acidity has become a common strategy for achieving high-performance OSCs. Metal oxides and two-dimensional materials as secondary dopants into PEDOT:PSS, respectively, as well as a replacement of PEDOT:PSS both exhibit immense potential for achieving high-performance OSCs due to their excellent electrical properties. Herein, we report a method utilizing a Fe3O4/GO magnetic nanocomposite as a secondary dopant for PEDOT:PSS to modulate its inherent properties for constructing high-efficiency OSCs. The magnetic nanocomposite hybrid HTL exhibits a suitable optical transmittance and higher work function. Meanwhile, it is found that the addition of Fe3O4/GO magnetic nanoparticles expands the domain of PEDOT and enhances the phase separation between PEDOT and PSS segments, thereby improving the conductivity of PEDOT:PSS. By fine-tuning the doping ratio of a Fe3O4/GO magnetic nanocomposite in PEDOT:PSS, the best power conversion efficiency of OSCs based on PM6:L8-BO was up to 18.91%. The notable enhancement of the device's performance was due to the enhanced hole mobility and the improved charge extraction, further complemented by the decreased likelihood of interface recombination brought about by the hybrid HTL. Compared with PEDOT:PSS-based OSCs, an enhanced stability of the hybrid HTL-based device was also obtained. In addition, the diverse adaptability of the hybrid HTL was demonstrated in enhancing the performance of OSCs that are based on PM6:Y6 and PBDB-T:ITIC. The effectiveness and versatility of a magnetic nanocomposite hybrid HTL present opportunities for achieving high-performance OSCs.

Improving the performance of organic solar cell via tuning the interfacial n-doping of cathode-modifying layer

Organic solar cells have been fabricated using thermally evaporated bathocuproine (BCP) and ytterbium n-doped BCP (BCP:Yb) to modify the interfaces of active layer and cathode. The device with 10 nm BCP presents open-circuit voltage of 0.791 V and fill factor of 0.670, greater than those (0.785 V and 0.636) of the device with 10 nm BCP:Yb, mostly due to that the BCP:Yb causes severe nonradiative recombination in active layer. The device with 1 nm BCP/9 nm BCP:Yb offers open-circuit voltage of 0.793 V, almost same as that of the device with 10 nm BCP, due to the two following reasons. Firstly, the interlayer of 1 nm BCP is able to separate active layer from BCP:Yb, thereby preventing the nonradiative recombination. Secondly, the BCP interlayer is so thin that the interfacial n-doping of Yb in it raises the Fermi level close to its lowest unoccupied molecular orbital level, whereby it forms ohmic contacts with active layer and BCP:Yb. Despite showing decreased fill factors, the devices with 10 nm BCP:Yb and 1 nm BCP/9 nm BCP:Yb give short-circuit current densities of 15.43 and 15.62 mA cm−2, respectively, larger than that (14.47 mA cm−2) of the device with 10 nm BCP. The power conversion efficiency based on 1 nm BCP/9 nm BCP:Yb is 8.11 %, higher than those based on 10 nm BCP (7.67 %) and 10 nm BCP:Yb (7.71 %). The current research indicates that tuning the interfacial n-doping of cathode-modifying layers is a facial and effective method to improve the performance of organic solar cells.

Optimizing the performance of perovskite-based organic solar cells via graphene integration as the hole transport layer: a comprehensive analysis

Optimizing the performance of perovskite-based organic solar cells via graphene integration as the hole transport layer: a comprehensive analysis