Developing polymer solar cells (PSCs) with high photovoltaic performance and mechanical robustness is one of the most urgent tasks to ensure their operational reliability and applicability in wearable devices. However,...

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.

The development of small-molecule acceptors (SMAs) has significantly enhanced the power conversion efficiency (PCE) of polymer solar cells (PSCs); however, the inferior mechanical properties of SMA-based PSCs often limit their long-term stability and application in wearable power generators. Herein, we demonstrate a simple and effective strategy for enhancing the mechanical robustness and PCE of PSCs by incorporating a high-molecular-weight (MW) polymer acceptor ( P A , P(NDI2OD-T2)). The addition of 10–20 wt % P A leads to a more than 4-fold increase in the mechanical ductility of the SMA-based PSCs in terms of the crack onset strain (COS). At the same time, the incorporation of P A into the active layer improves the charge transport and recombination properties, increasing the PCE of the PSC from 14.6 to 15.4%. The added P A s act as tie molecules, providing mechanical and electrical bridges between adjacent domains of SMAs. Thus, for the first time, we produce highly efficient and mechanically robust PSCs with a 15% PCE and 10% COS at the same time, thereby demonstrating their great potential as stretchable or wearable power generators. To understand the origin of the dual enhancements realized by P A , we investigate the influence of the P A content on electrical, structural, and morphological properties of the PSCs.

All-polymer solar cells (all-PSCs) exhibiting superior device stability and mechanical robustness have attracted considerable interests. Emerging polymerized small-molecule acceptors (PSMAs) have promoted the progress of all-PSCs exceeding power conversion efficiency...

tremendous progress in power conversion efficiency (PCE) and flexibility. [1a,2b,3] Although flexible OSCs exhibit high durability against bending, most of them are not suitable for application in wearable electronics due to the large tensile stress exerted on the devices by human body movements. Specifically, the human body consists of movable joints and elastic skin, which can exert a high stretchability of over 50% strain. [4] Consequently, it is imperative to develop stretchable OSCs beyond the flexible devices reported thus far.Although stretchable OSCs prepared via structural device engineering (i.e., a buckling method) have been reported by a few groups, [5] their manufacturing processes are typically complicated and expensive. Moreover, the stretching is limited to only one allowed direction, and it depends on the pattern of the wrinkled structures. [6] Intrinsically stretchable OSCs (IS-OSCs) have also been developed, utilizing electrodes from organic materials and liquid metal. All the constituent layers in the IS-OSCs can be stretched in every direction, distinguishable from the structurally engineered stretchable devices. [7] For example, Lipomi et al. reported IS-OSCs for the first time consisting of poly(3-hexylthiophene) (P3HT) and phenyl-C 61 -butyric acid methyl ester (PCBM) active layers on stretchable poly(dimethylsiloxane) substrates. [7c] Subsequently, Chen et al. prepared stretchable polymeric charge-transport layers consisting of poly[(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) and nitrile butadiene rubber (NBR) to construct IS-OSCs. The resulting device exhibited an initial PCE of 3% and maintained 94% of the performance under a 10% strain. [7a] Recently, we developed IS-OSCs with a higher PCE (≈11%) by using a thermoplastic polyurethane (TPU)-based substrate, a poly(3,4-ethylened ioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based transparent anode, and a liquid metal-based cathode. [7b] Nevertheless, the normalized PCEs of the PM6:Y7-based IS-OSCs rapidly decreased to ≈52% under 15% strain during in situ stretching cycles. [7b] This stretchability falls short of the requirements for practical application as wearable devices on human bodies.The limited stretchability of IS-OSCs is mainly due to the use of a mechanically brittle active layer containing small-molecule acceptors (SMAs). The use of strong light-absorbing SMAs and 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 (P A ) to polymer donor:smallmolecule acceptor blends. P A addition significantly enhances the stretchability and PCEs of the blends as the long P A chains function as molecular bridges ...

Combining hyperspectral and polarimetric imaging provides a powerful sensing modality with broad applications from astronomy to biology. Existing methods rely on temporal data acquisition or snapshot imaging of spatially separated detectors. These approaches incur fundamental artifacts that degrade imaging performance. To overcome these limitations, we present a stomatopod-inspired sensor capable of snapshot hyperspectral and polarization sensing in a single pixel. The design consists of stacking polarization-sensitive organic photovoltaics (P-OPVs) and polymer retarders. Multiple spectral and polarization channels are obtained by exploiting the P-OPVs’ anisotropic response and the retarders’ dispersion. We show that the design can sense 15 spectral channels over a 350-nanometer bandwidth. A detector is also experimentally demonstrated, which simultaneously registers four spectral channels and three polarization channels. The sensor showcases the myriad degrees of freedom offered by organic semiconductors that are not available in inorganics and heralds a fundamentally unexplored route for simultaneous spectral and polarimetric imaging.

The recent evolution of new polymer acceptors (P A s) using small-molecule building blocks with high light absorption has significantly increased the power conversion efficiency (PCE) of all-polymer solar cells (all-PSCs), but their mechanical properties are typically poor. Thus, poly[[N,N′-bis(2octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]alt-5,5′-(2,2′-bithiophene)] (N2200) is still considered one of the most successful P A s in all-PSCs. Herein, we report the development of new naphthalene dimide-based P A s (NDI-P A s) that enable the achievement of both superior PCEs and mechanical robustness of all-PSCs compared to those of N2200-based devices. Our approach is very simple and effective for constructing a series of P A s [PNDIHD/DT-x, where x = 0−1], consisting of two NDI units with different side chains (2-hexyldecyl (HD) and 2decyltetradecyl (DT)). The PNDIHD/DT-0.41-based all-PSCs with the poly [(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) polymer donor achieve a PCE of 9.3%, which outperforms the N2200-based device (PCE = 7.7%). This is mainly attributed to the enhanced charge generation and transport abilities of the PNDIHD/DT-0.41-based all-PSCs, as a result of optimal domain size and purity as well as high electron mobility. Importantly, the PBDB-T:PNDIHD/DT-0.41 blend shows excellent mechanical robustness, with a crack onset strain (COS) of 30% and a toughness of 7.5 MJ m −3 . In addition, a flexible polymer solar cell (FPSC) device with the PBDB-T:PNDIHD/DT-0.41 blend shows a high initial PCE of 6.73%, which is maintained over 6% even after bending 1500 times.

Blends of polymer donors (PDs) and small molecule acceptors (SMAs) have afforded highly efficient polymer solar cells (PSCs). However, most of the efficient PSCs are processed using toxic halogenated solvents, and they are mechanically fragile. Here, a new series of PDs by incorporating a hydrophilic oligo(ethylene glycol) flexible spacer (OEG‐FS) is developed, and efficient PSCs with a high power conversion efficiency (PCE) of 17.74% processed by a non‐halogenated solvent are demonstrated. Importantly, the incorporation of these OEG‐FSs into the PDs significantly increases the mechanical robustness and ductility of resulting PSCs, making them suitable for application as stretchable devices. The OEG‐FS alleviates excessive backbone rigidity of the PDs while enhancing their pre‐aggregation in the non‐halogenated solvent. In addition, the OEG‐FS in the PDs enhances PD‐SMA interfacial interactions and improves blend morphology, resulting in efficient charge generation and mechanical stress dissipation. The resulting PSCs demonstrate a superior PCE (17.74%) and high crack‐onset strain (COS = 10.50%), outperforming the PSCs without OEG (PCE = 15.64% and COS = 2.99%). Importantly, intrinsically stretchable (IS) PSCs containing the PD featuring OEG‐FS exhibit a high PCE (12.05%) and stretchability (maintaining 80% of the initial PCE after 22% strain), demonstrating their viability for wearable applications.