Organic charge transfer complexes (CTCs) or electron donor–acceptor complexes have been intensively studied as organic semiconductors or organic conductors in organic electronics. Herein, the composite of CTCs and single‐walled carbon nanotubes (SWCNTs) is studied as both p‐type and n‐type thermoelectric materials for flexible thermoelectric generators. CTCs are formed by [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) derivatives with different side chains as electron donors and 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) as electron acceptors. The thermoelectric properties of the composites as well as the effect of side chains in BTBT derivatives are investigated. It is found that the PhBTBT–F4TCNQ/SWCNT composite film shows the highest p‐type power factor of 244.3 µW m−1 K−2; while the C8BTBT–F4TCNQ/SWCNT composite film exhibits the highest n‐type power factor of 105.1 µW m−1 K−2. The thermoelectric module based on five p–n junctions of C8BTBT–F4TCNQ/SWCNT exhibits the highest output voltage of 13.1 mV and output power of 340 nW under a 38 K temperature gradient. This device performance is mainly generated from the moderate carrier concentrations and low film defects in the n‐type C8BTBT–F4TCNQ/SWCNT composite film.
Daytime passive radiative cooling has emerged as an energy-saving cooling technique. However, market penetration of current daytime passive radiative cooling-related membranes is still miniscule due to deficiencies in scalability, recyclability, and robustness. This work successfully addresses these issues by concurrently imparting the following features in a designed polymeric cooler: (1) cost-effective and recyclable raw materials that highlight the sustainability; ( 2) scalable yet exquisite structureengineering strategy to afford superb light scattering performance;(3) malleable under facile conditions to fit complex surface conformably. Specifically, our cooling membrane is solely composed of a mass chemical, polyvinyl butyral, which forms a supramolecular network with the polymer−air interface as light scattering sites and −C−O−C− bonds as infrared emitters. The structure of the polyvinyl butyral membrane is exquisitely organized via kinetical arrest of network-forming phase separation. The spatial size, contrast, and distribution of phase domains can be finely manipulated via tuning the composition routes and depth of phase separation. The optimized membrane demonstrates all-day and all-climate cooling with a 7.3 °C subambient cooling and 62 W/m 2 cooling power. In addition to this superb cooling performance, this membrane uniquely affords a collective of multiple features, such as cost effectiveness, recyclability, and hydrophobicity.
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