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The electro-active third component (BID)-incorporated PM6-B10-based organic solar cell shows a high performance (PCE = 17.2%) and mechanical stretchability (COSavg = 11.4%), outperforming the PM6-based device (PCE = 15.8%, COSavg = 2.0%).

We report a new molecular design of sequentially regular polymerized small-molecule-acceptors containing flexible spacer (FS) units (PYFS-Reg) to achieve all-polymer solar cells with both high-performance and mechanical stretchability.

We develop a series of polymer donors containing carbazole-based units (CBT) to achieve high-performance (PCE of 15.54%) and thermally stable PSCs.

We develop a non-covalently fused ring acceptor, CPDT–ICMe, to achieve P3HT-based organic solar cells with high-performance (8.17%) and excellent thermal stability.

Highly efficient (PCE = 13.1%) and stretchable (strain at PCE80% = 34%) IS-OSCs are developed using a molecular interdiffusion-assisted TPU-PEDOT:PSS bilayers with excellent adhesion properties.

In this study, two wide-bandgap PM7 polymer derivatives are developed via simple structural modification of the fused-accepting unit by incorporating ester groups on terthiophene at different positions (i.e., two ester groups on the outer thiophenes (PM7 D1) and on the central thiophene (PM7 D2)). This simple modification creates a higher-energy light absorption window, providing better complementary light harvesting with naphthalenediimide-based acceptor, P(NDI2HD-Se). As a result, PM7 D1-based all-polymer solar cells (all-PSCs) exhibit a high power conversion efficiency (PCE) of 9.13%, which outperforms that of the PM7-based all-PSC (PCE = 6.93%). Importantly, the ester structural modification has significant impact on the thin-film mechanical ductility and robustness. For example, elongation properties of PM7 D1 and PM7 D2 pristine films are significantly improved by ca. 2.5 times compared to that of PM7. This result is attributed to the flexible ester groups, which are able to effectively compensate for applied stress. The improved ductile properties of PM7 D1 and PM7 D2 also affect the mechanical ductility of the blend films, leading to 1.5-fold increase in crack onset strain compared with that of the PM7 blend film. Therefore, we demonstrate that the introduction of ester groups in conjugated polymers provides a simple and promising strategy for future stretchable electronics.

The selection of interfacial layers in organic solar cells (OSCs) is crucial for enhancing their power conversion efficiency (PCE) and operational stability. PEDOT:PSS is the most widely used hole transport layer (HTL) for high-performance OSCs; however, device stability is often severely degraded, owing to the strong acidity and hygroscopicity of PEDOT:PSS. Herein, we report a new efficient HTL system comprising an oligo(aniline) host (PBD) and an aryl sulfonic acid dopant (PFBSA), and demonstrate its use in high-performance OSC devices. Desirable properties like solvent orthogonality, high transmittance, excellent conductivity, and appropriate work function establish the suitability of the PBD:PFBSA film as an HTL. Thus, a PBD:PFBSA HTL is employed in the PM6:Y6-based OSC system to achieve a PCE of 15.24%, which is comparable to that of the PEDOT:PSS HTL-based OSC. Importantly, the PBD:PFBSA HTL-based OSC exhibits significantly higher device stability than the PEDOT:PSS HTL. We investigate the film properties of the PBD:PFBSA HTL to elucidate the origin of the superior device stability. Our results highlight the successful design of a protonic acid-doped oligo(aniline)-based material and its practical application as an effective HTL for OSCs.

While the power conversion efficiencies (PCEs) of organic solar cells (OSCs) have been dramatically increased through the development of small molecular acceptors (SMAs), achieving eco-friendly solution processability of OSCs is a crucial prerequisite for their practical application. In this study, we develop three new, green solvent-processable SMAs (YSe–C3, YSe–C6, and YSe–C9) with different outer side-chains (n-propyl (C3), n-hexyl (C6), and n-nonyl (C9)), affording high-performance OSCs with non-halogenated solvent (o-xylene)-processed active layers. Also, the impact of both outer and inner side-chain engineering of these SMAs on the performance of eco-friendly fabricated OSCs is systematically investigated. The outer side-chain structure has a much more significant impact than the inner side-chain. For example, the PM6:YSe–C6 blend affords high-performance OSCs with a power conversion efficiency (PCE) of over 16%, whereas the PCEs of the YSe–C3- and YSe–C9-based OSCs are only 11–14%. The lower PCEs of PM6:YSe–C3 and C9 are mainly attributed to reduced electron mobility and increased charge recombination, resulting from aggregate-containing non-optimal blend morphologies. Interestingly, the well-optimized morphology of the YSe–C6-based blend also affords OSC devices with active layer thickness-independent PCEs, up to a thickness of >400 nm, demonstrating the great potential for large-area device manufacturing via an eco-friendly printing process. Thus, optimizing the outer side-chain structure of Y-series SMAs is essential for producing green solvent-processed high-performance OSCs.

Recent advances in the power conversion efficiency (PCE) of organic solar cells (OSCs) have greatly enhanced their commercial viability. Considering the technical standards (e.g., mechanical robustness) required for wearable electronics, which are promising application platforms for OSCs, the development of fully stretchable OSCs (f-SOSCs) should be accelerated. Here, a comprehensive overview of f-SOSCs, which are aimed to reliably operate under various forms of mechanical stress, including bending and multidirectional stretching, is provided. First, the mechanical requirements of f-SOSCs, in terms of tensile and cohesion/adhesion properties, are summarized along with the experimental methods to evaluate those properties. Second, essential studies to make each layer of f-SOSCs stretchable and efficient are discussed, emphasizing strategies to simultaneously enhance the photovoltaic and mechanical properties of the active layer, ranging from material design to fabrication control. Key improvements to the other components/layers (i.e., substrate, electrodes, and interlayers) are also covered. Lastly, considering that f-SOSC research is in its infancy, the current challenges and future prospects are explored.

In this work, the impact of temperature-dependent aggregation behaviors in benzodithiophene (BDT)-based polymer donors (PDs) on the electrical, morphological, and photovoltaic performances of all-p...

The aggregation properties of conjugated polymers can play a crucial role in their thin film structures and performance of electronic devices. Control of these aggregated structures is particularly important in producing efficient all-polymer solar cells (all-PSCs), considering that strong demixing of the polymer donor and polymer acceptor typically occurs during film formation because of the low entropic contribution to the thermodynamics of the system. Here, three naphthalenediimide (NDI)-based polymer acceptors with different backbone chlorination patterns are developed to investigate the effect of the chlorination patterns on the aggregation tendencies of the polymer acceptors, which greatly influence their crystalline structures, electrical properties, and device performances of the resultant all-PSCs and organic field-effect transistors (OFETs). The counterparts of NDI units, dichlorinated bithiophene (Cl2T2), monochlorinated bithiophene (ClT2), and dichlorinated thienylene-vinylene-thienylene (Cl2TVT), are employed to synthesize a series of P(NDIOD-Cl2T2), P(NDIOD-ClT2), and P(NDIOD-Cl2TVT) polymers. The P(NDIOD-Cl2T2) polymer takes advantage of strong noncovalent bonding induced by its chlorine substituents, resulting in the formation of optimal face-on oriented crystalline structures which are suitable for efficient all-PSC devices. In comparison, the P(NDIOD-Cl2TVT) polymer forms bimodal crystalline structures in thin films to yield optimal performances in the resultant OFETs. When the three chlorinated polymers are applied to all-PSCs with the PBDTTTPD polymer donor, P(NDIOD-Cl2T2) achieves a maximum power conversion efficiency (PCE) of 7.22% with an appropriate blend morphology and high fill factor, outperforming P(NDIOD-ClT2) (PCE = 4.80%) and P(NDIOD-Cl2TVT) (PCE = 5.78%). Our observations highlight the effectiveness of the chlorination strategy for developing efficient polymer acceptors and demonstrate the important role of polymer aggregation in modulating the blend morphology and all-PSC performance.

The operation stability of polymer solar cells (PSCs) is one of the most important prerequisites for their practical use. In this work, we report a new acceptor–donor–acceptor (A–D–A) triad-type small molecule, 5TRh-PCBM, as a compatibilizer for enhancing the thermal stabilities and mechanical properties of efficient PSCs while increasing their power conversion efficiencies (PCEs). This multifunctional 5TRh-PCBM molecule, consisting of an oligothiophene segment as the central core and fullerene derivatives as the end groups, is designed to enable strong interactions between the 5TRh-core with various types of efficient polymer donors containing thiophene or fused-thiophene units, while the end fullerene groups preferentially interact with PCBM acceptors. To examine the effectiveness of this molecular compatibilizer, PSCs with different donors (PTB7-Th, PBDB-T, and P3HT) have been fabricated and tested, with addition of various amounts of 5TRh-PCBM. The addition of 5 and 10 wt% of 5TRh-PCBM significantly enhances the thermal and mechanical stabilities of all tested PSCs. Importantly, unlike typical compatibilizers, the addition of 5TRh-PCBM can increase the PCEs of the PSCs due to its light harvesting capability. In particular, the PCE of PTB7-Th:PCBM-based PSCs is increased from 9.37% to 10.09% with the 5 wt% addition of 5TRh-PCBM. Our comprehensive investigations have revealed the effects of 5TRh-PCBM on the optical, morphological, photovoltaic, and mechanical properties of molecularly engineered PSCs.

(1) Background: Lumbar spinal stenosis (LSS) causes uncomfortable neuropathic symptoms, which can negatively affect osteoporosis. The aim of this study was to investigate the effect of LSS on bone mineral density (BMD) in patients treated with one of three oral bisphosphonates (ibandronate, alendronate and risedronate) for initially diagnosed osteoporosis. (2) Methods: We included 346 patients treated with oral bisphosphonates for three years. We compared annual BMD T-scores and BMD increases between the two groups according to symptomatic LSS. The therapeutic efficacies of the three oral bisphosphonates in each group were also evaluated. (3) Results: Annual and total increases in BMD were significantly greater in group I (osteoporosis) compared to group II (osteoporosis + LSS). The total increase in BMD for three years was significantly greater in the ibandronate and alendronate subgroups than that in the risedronate subgroup (0.49 vs. 0.45 vs. 0.25, p < 0.001). Ibandronate showed a significantly greater increase in BMD than that of risedronate in group II (0.36 vs. 0.13, p = 0.018). (4) Conclusions: Symptomatic LSS may interfere with the increase in BMD. Ibandronate and alendronate were more effective in treating osteoporosis than risedronate. In particular, ibandronate was more effective than risedronate in patients with both osteoporosis and LSS.

All-polymer solar cells (all-PSCs) consisting of polymer donors (PDs) and polymer acceptors (PAs) have drawn tremendous research interest in recent years. It is due to not only their tunable optical, electrochemical, and structural properties, but also many superior features that are not readily available in conventional polymer-fullerene solar cells (fullerene-PSCs) including long-term stability, synthetic accessibility, and excellent film-forming properties suitable for large-scale manufacturing. Recent breakthroughs in material design and device engineering have driven the power conversion efficiencies (PCEs) of all-PSCs exceeding 11%, which is comparable to the performance of fullerene-PSCs. Furthermore, outstanding mechanical durability and stretchability have been reported for all-PSCs, which make them stand out from the other small molecule-based PSCs as a promising power supplier for wearable electronic devices. This review provides a comprehensive overview of the important work in all-PSCs, in which pertinent examples are deliberately chosen. First, we describe the key components that enabled the recent progresses of all-PSCs including rational design rules for efficient PDs and PAs, blend morphology control, and light harvesting engineering. We also review the recent work on the understanding of the stability of all-PSCs under various external conditions, which highlights the importance of all-PSCs for future implementation and commercialization. Finally, because all-PSCs have not yet achieved their full potential and are still undergoing rapid development, we offer our views on the current challenges and future prospects.

Study design A propensity score-matched cohort study. Objective The objective of this study was to compare the radiologic and clinical outcomes of camptocormia in Parkinson disease (PD) with degenerative sagittal imbalance (DSI) patients. Summary of background data Camptocormia in PD and DSI could be characterized by a dynamic deformity. However, no study has directly evaluated the outcomes of patients with camptocormia and DSI. Methods Thirteen consecutive PD patients undergoing surgical correction for camptocormia were matched in a 1-to-2 format with 26 patients in the DSI group by propensity score-matching. Radiologic outcomes, including paravertebral muscle changes, and clinical outcomes were compared between the 2 groups. The rate of proximal junctional problems and reoperations were assessed. Results PD patients with camptocormia had significantly greater preoperative coronal and sagittal malalignments (29.9 vs. 16.9 mm, P=0.019; 142.8 vs. 64.4 mm, P=0.0001, respectively) and weakness of paravertebral muscles compared with the DSI patients. Regarding the clinical outcomes, reoperations were significantly higher in the camptocormia group, compared with the DSI group (53.8% vs. 7.7%, P=0.001). Moreover, proximal junctional failure was developed in 8 patients in the camptocormia group, while 1 patient in the DSI group (61.5% vs. 3.8%, P=0.0001). In subgroup analysis, independent risk factors for the proximal junctional failure were the total fusion levels (hazard ratio=0.26, P=0.018) and the degree of fatty changes of the paravertebral muscles (hazard ratio=1.15, P=0.048). Conclusions PD patients undergoing spinal surgery for camptocormia had global malalignment and higher rates of complications compared with DSI patients. Patients should be appropriately counseled regarding the increased risk of operative complications and closely followed for incipient failure.