Molecular Control of the Donor/Acceptor Interface Suppresses Charge Recombination Enabling High-Efficiency Single-Component Organic Solar Cells.

Single-component organic solar cells based on double cable polymers have achieved remarkable performance, with DCPY2 reaching a high efficiency of over 13%. In this study, DCPY2 is further optimized with an efficiency of 13.85%, maintaining a high fill factor (FF) without compromising the short circuit current. Despite its intermixed morphology, DCPY2 shows a reduced recombination rate compared to their binary counterpart (PBDB-T:Y-O6). This slower recombination in DCPY2 is attributed to the reduced wavefunction overlap of delocalized charges, achieved by spatially separating the donor and acceptor units with an alkyl linker, thereby restricting the recombination pathways. Adding 1,8-diiodooctane (DIO) into DCPY2 further reduced the recombination rate by facilitating acceptor aggregation, allowing free charges to become more delocalized. The DIO-assisted aggregation in DCPY2 (5% DIO) is evidenced by an increased pseudo-pure domain size of Y-O6. Fine molecular control at the donor/acceptor interface in the double-cable polymer achieves reduced non-geminate recombination under efficient charge generation, increased mobility, and charge carrier lifetime, thereby achieving superior performance. Nevertheless, the FF is still limited by relatively low mobility compared to the blend, suggesting the potential for further mobility improvement through enhanced higher-dimensional packing of the double-cable material.

High-Detectivity All-Polymer Photodiode Empowers Smart Vitality Surveillance and Computational Imaging Rivaling Silicon Diodes.

Near-infrared (NIR) organic photodetectors (OPDs), particularly all-polymer-based ones, hold substantial commercial promise in the healthcare and imaging sectors. However, the process of optimizing their active layer composition to achieve highly competitive figures of merit lacks a clear direction and methodology. In this work, celebrity polymer acceptor PY-IT into a more NIR absorbing host system PBDB-T:PZF-V, to significantly enhance the photodetection competence, is introduced. The refined all-polymer ternary broadband photodetector demonstrates superior performance metrics, including experimentally measured noise current as low as 6 fA Hz-1/2, specific detectivity reaching 8 × 1012 Jones, linear dynamic range (LDR) of 145 dB, and swift response speed surpassing 200 kHz, striking a fair balance between sensitivity and response speed. Comprehensive morphological and photophysical characterizations elucidate the mechanisms behind the observed performance enhancements in this study, which include reduced trap density, enhanced charge transport, diminished charge recombination, and balanced electron/hole mobilities. Moreover, the practical deployment potential of the proof-of-concept device in self-powered mode is demonstrated through their application in a machine learning-based cuffless blood pressure (BP) estimation system and in high-resolution computational imaging across complex environments, where they are found to quantitatively rival commercial silicon diodes.

Isomerization of Benzothiadiazole Yields a Promising Polymer Donor and Organic Solar Cells with Efficiency of 19.0.

The exploration of high-performance and low-cost wide-bandgap polymer donors remains critical to achieve high-efficiency nonfullerene organic solar cells (OSCs) beyond current thresholds. Herein, the 1,2,3-benzothiadiazole (iBT), which is an isomer of 2,1,3-benzothiadiazole (BT), is used to design wide-bandgap polymer donor PiBT. The PiBT-based solar cells reach efficiency of 19.0%, which is one of the highest efficiencies in binary OSCs. Systemic studies show that isomerization of BT to iBT can finely regulate the polymers' photoelectric properties including i) increasing the extinction coefficient and photon harvest, ii) downshifting the highest occupied molecular orbital energy levels, iii) improving the coplanarity of polymer backbones, iv) offering good thermodynamic miscibility with acceptors. Consequently, the PiBT:Y6 bulk heterojunction (BHJ) device simultaneously reaches advantageous nanoscale morphology, efficient exciton generation and dissociation, fast charge transportation, and suppressed charge recombination, leading to larger VOC of 0.87 V, higher JSC of 28.2 mA cm-2, greater fill factor of 77.3%, and thus higher efficiency of 19.0%, while the analog-PBT-based OSCs reach efficiency of only 12.9%. Moreover, the key intermediate iBT can be easily afforded from industry chemicals via two-step procedure. Overall, this contribution highlights that iBT is a promising motif for designing high-performance polymer donors.

Step-by-Step Modulation of Crystalline Features and Exciton Kinetics for 19.2% Efficiency Ortho-Xylene Processed Organic Solar Cells.

With plenty of popular and effective ternary organic solar cells (OSCs) construction strategies proposed and applied, its power conversion efficiencies (PCEs) have come to a new level of over 19% in single-junction devices. However, previous studies are heavily based in chloroform (CF) leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component. Herein, we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy, named BTP-BO-3FO with enlarged bandgap, brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9, processed by CF and ortho-xylene (o-XY). With detailed analyses supported by a series of experiments, the best PCE of 19.24% for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif, which furthermore nourishes a favorable charge generation and recombination behavior. Likewise, over 19% PCE can be achieved by replacing spin-coating with blade coating for active layer deposition. This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance, hence, will be instructive to other ternary OSC works in the future.

[Chemical constituents from whole plants of Aconitum tanguticum].

Nineteen compounds were isolated from the whole plants of Aconitum tanguticum by means of various of chromatographic techniques such as silica gel, ODS, sephadex LH-20 and preparative HPLC, and their structures were elucidated as syringin (1), vanillic acid-4-O-beta-D-allopyranoside (2), (E) -ferulic acid 4-O-beta-D-allopyranoside (3), (E) -ferulic acid-4-O-beta-glucopysoside (4), (E) -sinapic acid-4-O-beta-glucopyranoside (5), (E) 4-hydroxycinnamyl alcohol 4-O-beta-D-glucopyranoside (6), quercetin 3-O-alpha-L-rhamnopyranosyl-(1 --> 2) -[alpha-L-rhamnopyranosyl-(1 --> 6)] -beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (7), kaempferol 3-O-alpha-L-rhamnopyranosyl-(1 --> 2) - [alpha-L-rhamnopyranosyl-(1 --> 6)] -beta-D-galactopyranside-7-O-alpha-L-rhamnopyranoside (8), quercetin 3-O-alpha-L-rhamnopyranosyl-(1 --> 6) -beta-D-glucopyranoside-7-O-alpha-L-rhamnopyranoside (9), kaempferol 3-O-[beta-D-glucopyranosyl-(1 --> 3)-(4-O-trans-p-coumaroyl) ] -alpha-L-rhamnopyranosyl-(1 --> 6) -beta-D-galactopyranside-7-O-alpha-L-rhamnopyranoside (10), quercetin 3-O- [beta-D-glucopyranosyl-(1 --> 3 ) -(4-O-trans-p-coumaroyl)] -alpha-L-rhamnopyranosyl-(1--> 6) -beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (11), salidroside (12), 2-(3,4-dihydroxyphenyl) ethanol 1-O-beta-D-glucopyranoside (13), (7S, 8R) -dehydrodiconiferyl alcohol-9'-O-beta-D-glucopyranoside (14), citrusin B (15), heteratisine (16), tanaconitine (17), shanzhiside methyl ester (18) and icariside B1 (19). Except compounds 4, 13, 16 and 17, the other compounds were separated from the species for the first time.