High efficiency and mechanical robustness are both crucial for the practical applications of all‐polymer solar cells (all‐PSCs) in stretchable and wearable electronics. In this regard, a series of ...new polymer acceptors (PAs) is reported by incorporating a flexible conjugation‐break spacer (FCBS) to achieve highly efficient and mechanically robust all‐PSCs. Incorporation of FCBS affords the effective modulation of the crystallinity and pre‐aggregation of the PAs, and achieves the optimal blend morphology with polymer donor (PD), increasing both the photovoltaic and mechanical properties of all‐PSCs. In particular, an all‐PSC based on PYTS‐0.3 PA incorporated with 30% FCBS and PBDB‐T PD demonstrates a high power conversion efficiency (PCE) of 14.68% and excellent mechanical stretchability with a crack onset strain (COS) of 21.64% and toughness of 3.86 MJ m‐3, which is significantly superior to those of devices with the PA without the FCBS (PYTS‐0.0, PCE = 13.01%, and toughness = 2.70 MJ m‐3). To date, this COS is the highest value reported for PSCs with PCEs of over 8% without any insulating additives. These results reveal that the introduction of FCBS into the conjugated backbone is a highly feasible strategy to simultaneously improve the PCE and stretchability of PSCs.
New polymer acceptors (PAs) are developed by embedding flexible conjugation‐break spacer (FCBS) units into the rigid backbones. The incorporation of FCBS affords effective modulation of the crystallinity and pre‐aggregation of the PA and attains optimal blend morphology. As a result, the all‐polymer solar cells exhibit both a high efficiency of 14.68% and excellent mechanical robustness with a crack onset strain of 21.64%.
All‐polymer solar cells (all‐PSCs) are a highly attractive class of photovoltaics for wearable and portable electronics due to their excellent morphological and mechanical stabilities. Recently, new ...types of polymer acceptors (PAs) consisting of non‐fullerene small molecule acceptors (NFSMAs) with strong light absorption have been proposed to enhance the power conversion efficiency (PCE) of all‐PSCs. However, polymerization of NFSMAs often reduces entropy of mixing in PSC blends and prevents the formation of intermixed blend domains required for efficient charge generation and morphological stability. One approach to increase compatibility in these systems is to design PAs that contain the same building blocks as their polymer donor (PD) counterparts. Here, a series of NFSMA‐based PAs P(BDT2BOY5‐X), (X = H, F, Cl) are reported, by copolymerizing NFSMA (Y5‐2BO) with benzodithiophene (BDT), a common donating unit in high‐performance PDs such as PBDB‐T. All‐PSC blends composed of PBDB‐T PD and P(BDT2BOY5‐X) PA show enhanced molecular compatibility, resulting in excellent morphological and electronic properties. Specifically, PBDB‐T:P(BDT2BOY5‐Cl) all‐PSC has a PCE of 11.12%, which is significantly higher than previous PBDB‐T:Y5‐2BO (7.02%) and PBDB‐T:P(NDI2OD‐T2) (6.00%) PSCs. Additionally, the increased compatibility of these all‐PSCs greatly improves their thermal stability and mechanical robustness. For example, the crack onset strain (COS) and toughness of the PBDB‐T:P(BDT2BOY5‐Cl) blend are 15.9% and 3.24 MJ m–3, respectively, in comparison to the PBDB‐T:Y5‐2BO blends at 2.21% and 0.32 MJ m–3.
A new class of polymer acceptors (PAs, P(BDT2BOY5‐X)) consisting of benzodithiophene (BDT) and non‐fullerene small molecule‐accepting units is developed, which shows excellent material compatibility with an efficient BDT‐based polymer donor (PD). The resulting all‐polymer solar cells show excellent photovoltaic efficiency, thermal stability, and mechanical robustness at the same time, benefitting from the high chemical and molecular compatibilities between PD and PA.
Recent progress in highly efficient perovskite solar cells (PSCs) has been made by virtue of interfacial engineering on 3D perovskite surfaces for their defect control, however, the structural ...stability of the modified interface against external stimuli still remains unresolved. Herein, 4‐dimethylaminopyridine (DMAP) is introduced to develop a facile technique for selectively passivating the grain boundary (GB) and controlling the topographical boundary of the perovskite surface near the GB. Through the surface treatment of DMAP, strongly bound DMAP crystals are selectively formed at the GB, which serves two functions: nonradiative recombination at GB is effectively reduced by healing the uncoordinated Pb2+ while adhesion strength between the perovskite and the poly(triaryl amine) (PTAA) polymer is significantly enhanced by a mechanical interlock effect. A planar PSC with DMAP treatment exhibits a champion power conversion efficiency of 22.4%, which is not only much higher than the 20.04% observed for a nontreated control device, but also the highest among the planar PSCs using PTAA polymers as a hole transport material. Furthermore, the use of DMAP leads to a substantial improvement in the device stability under damp‐heat test and light irradiation.
4‐Dimethylaminopyridine (DMAP) is introduced to develop a facile technique for selectively passivating grain boundaries (GB) and controlling the topographical boundary of perovskite surfaces near GBs. A power conversion efficiency of 22.4% is achieved for a planar perovskite solar cell with DMAP treatment and the device stability under damp‐heat and light irradiation is improved.
The outstanding performance (sheet resistance of 5 Ω sq–1 at transmittance of 90%) and strongly adhesive (30.7 J m–2) silver nanowires (AgNWs) are fabricated using flash‐induced plasmonic welding ...(FPW) based on theoretical research of photothermal interactions. The FPW‐processed AgNWs are utilized as electrodes of a transparent flexible energy harvester, and this device exhibits excellent transmittance and high electric output performance. The FPW methodology provides a high‐tech solution for transparent flexible electronics.
RGO flakes are homogeneously dispersed in a Cu matrix through a molecular‐level mixing process. This novel fabrication process prevents the agglomeration of the RGO and enhances adhesion between the ...RGO and the Cu. The yield strength of the 2.5 vol% RGO/Cu nanocomposite is 1.8 times higher than that of pure Cu. The strengthening mechanism of the RGO is investigated by a double cantilever beam test using the graphene/Cu model structure.
As an alternative to the brittle and expensive indium tin oxide (ITO) transparent conductor, a very simple, room‐temperature nanosoldering method of Ag nanowire percolation network is developed with ...conducting polymer to demonstrate highly flexible and even stretchable transparent conductors. The drying conducting polymer on Ag nanowire percolation network is used as a nanosoldering material inducing strong capillary‐force‐assisted stiction of the nanowires to other nanowires or to the substrate to enhance the electrical conductivity, mechanical stability, and adhesion to the substrate of the nanowire percolation network without the conventional high‐temperature annealing step. Highly bendable Ag nanowire/conducting polymer hybrid films with low sheet resistance and high transmittance are demonstrated on a plastic substrate. The fabricated flexible transparent electrode maintains its conductivity over 20 000 cyclic bends and 5 to 10% stretching. Finally, a large area (A4‐size) transparent conductor and a flexible touch panel on a non‐flat surface are fabricated to demonstrate the possibility of cost‐effective mass production as well as the applicability to the unconventional arbitrary soft surfaces. These results suggest that this is an important step toward producing intelligent and multifunctional soft electric devices as friendly human/electronics interface, and it may ultimately contribute to the applications in wearable computers.
A very simple, room‐temperature nanosoldering of a Ag nanowire percolation network by conducting‐polymer‐assisted nanowire joining is developed to demonstrate highly flexible, and even stretchable, transparent conductors. Furthermore, a large area (A4‐size) transparent conductor and a flexible touch panel on a non‐flat surface are fabricated to demonstrate the possibility of cost‐effective mass production and the applicability to the unconventional arbitrary soft, non‐flat surfaces.
Organic solar cells (OSCs) are promising wearable/stretchable power sources, but the development of high‐performance intrinsically stretchable OSCs (IS‐OSCs) has rarely been reported. Herein, IS‐OSCs ...exhibiting high power conversion efficiencies (PCEs) (>12%) and excellent stretchability are developed by constructing efficient and mechanically robust active layers via the addition of a high‐molecular weight polymer acceptor (PA) to polymer donor:small‐molecule acceptor blends. PA addition significantly enhances the stretchability and PCEs of the blends as the long PA chains function as molecular bridges between different domains, effectively dissipating mechanical stresses and improving charge transport. The IS‐OSCs with 20 wt% PA content exhibit a high PCE of 11.7% and excellent stretchability, retaining 84% of the initial PCE after 100 cycles of repetitive stretching/releasing at a 15% strain. To the best of the authors’ knowledge, the device represents the best IS‐OSC performance reported to date in terms of PCE and stretchability, demonstrating the great potential of IS‐OSCs as an efficient and wearable power generator.
Herein, high‐performance, intrinsically stretchable‐organic solar cells, which maintain 84% of the initial power conversion efficiency after 100 cycles of stretching/releasing under 15% strain are realized. High performance is achieved by efficient and mechanically robust active layers constructed by adding a high‐molecular weight polymer acceptor into polymer donor:small‐molecule acceptor blends.
All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability ...in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices.
Silver nanowire (AgNW) random meshes have attracted considerable attention as flexible and high‐performance transparent electrodes. Notably, post‐treatment of the AgNW random meshes, such as thermal ...annealing, is usually required to guarantee comparable optical transparency and electrical conductivity to commercial indium tin oxide (ITO). Here, the integral elements of preparing a high‐performance, large‐area AgNW random mesh network are discussed. High‐performance nanostructured transparent electrodes can be obtained without any post‐treatment, thereby relieving the restrictions related to the substrate. Solvent washing and a large‐area spray‐coating method effectively reduce the wire–wire contact resistances, thus reducing or eliminating the requirement for post‐treatment.
Solvent washing and spraying of silver nanowires decrease the sheet resistance of silver nanowire networks dramatically. The newly suggested methods eliminate post treatments such as annealing and pressing, which have been considered essential processes to reduce the sheet resistance and obtain ITO‐comparable transparent electrodes.
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