Polymer/lead halide perovskite composites are a promising platform for wearable optoelectronic devices. In particular, one-dimensional nanocomposites are considered core materials for solar energy conversion textiles and optical sensors. Herein, we designed stretchable photodetectors incorporating thin and uniform polymer/perovskite composite nanofibers produced by electrospinning of a polymer/perovskite precursor solution.During the reaction of precursors in the as-spun nanofiber, protruding perovskite nanoplates on the fiber surface and embedded nanoparticles within the fiber were formed, showing double photoluminescence emissions. Furthermore, the mechanical behavior of the nanofibers on a rubbery substrate strongly depends on their orientation angle (α) with respect to the applied tensile force. As α decreases, the loaded stress is significantly reduced, which contributes to a stretchability of up to 15% strain for any orientation. The excellent percolation of perovskite nanoparticles leads to high photocurrents under green and red light illumination. At 15% strain, the responsivity and detectivity of the stretchable photodetector at λ = 550 nm were 51.2 mA W −1 and 2.23 × 10 11 Jones, respectively. The device performance was well retained during mechanical deformation and stability tests. This thin and stretchable device was also applied to a wearable photodetector to demonstrate its great potential as a wearable image sensor.

Lead halide perovskite nanocrystals have emerged as core materials for next-generation optoelectronics because of their high quantum yield, tunable band gaps, and facile mass production based on solution processes. Conventional perovskite luminescent solar concentrators (LSCs) are prepared using nanocrystal/polymer composite films. They require a multistep fabrication process, including the presynthesis of nanocrystals and deposition of nanocrystal–polymer mixed solutions under controlled rheological parameters. Herein, we introduce highly efficient perovskite LSCs designed with electrospun perovskite/polymer composite nanofibers. Methylammonium lead bromide (MAPbBr3) nanocrystals were synthesized via a polymer-mediated in situ growth process during electrospinning. The annealing-free and one-step fabricated luminescent composite nanofiber mats exhibited excellent photoluminescence characteristics. The light absorption, transmittance, and optical haze of the nanofiber mats were further improved after poly(methyl methacrylate) (PMMA) layers were deposited. Nanofiber mats passivated with PMMA were used as an LSC film, exhibiting impressive optical efficiencies of 11.18% for geometry (G) factors of 2.77. The corresponding PCE of the Si solar cells coupled with LSC was 2.35%. This value was almost retained under continuous 1 sun illumination for 120 h. The LSCs also demonstrate their great potential in indoor environments, as they exhibit an excellent PCE of 5.3% under a white light illuminance of 1000 lx.

The surface passivation of metal oxide electron-transport layers (ETLs) is a powerful strategy for realizing high-performance perovskite solar cells. The surface properties of ETLs strongly influence carrier injection and transfer dynamics; therefore, control of the carrier trap density is crucial. Semiconducting small molecules are considered suitable materials for surface passivation. However, they are expensive and vulnerable to humid atmospheres. Ultrathin polymer layers can have poor surface coverage owing to their spinodal dewetting. In this study, we employ adipoyl chloride as an organic ligand for the chemically robust and efficient surface passivation of SnO2 ETLs. Through the strong coordination of diacyl-metal cations, acyl groups are adsorbed onto the SnO2 surfaces, and the density of oxygen vacancies is significantly reduced. Furthermore, the changing surface properties of the SnO2 ETLs also contribute to the improvement of perovskite morphologies. The deeper energy levels and reduced defect density of the ETLs promote electron injection and transfer at the perovskite and ETL interface. The enlarged perovskite grains are accompanied by improved electron mobility and reduced grain-boundary density. The resulting power conversion efficiency (PCE) increases from 19.36 to 21.41%. The normalized PCE is retained at 90.4% of the initial value for 720 h under 1 sun illumination without the encapsulation of the devices.

Conductive fibers are core materials in textile electronics for the sustainable operation of devices under mechanical stimuli. Conventional polymer−metal core−sheath fibers were employed as stretchable electrical interconnects. However, their electrical conductivity is severely degraded by the rupture of metal sheaths at low strains. Because the core−sheath fibers are not intrinsically stretchable, designing a stretchable architecture of interconnects based on the fibers is essential. Herein, we introduce nonvolatile droplet−conductive microfiber arrays as stretchable interconnects by employing interfacial capillary spooling, motivated by the reversible spooling of capture threads in a spider web. Polyurethane (PU)−Ag core−sheath (PU@Ag) fibers were prepared by wet-spinning and thermal evaporation. When the fiber was placed on a silicone droplet, a capillary force was generated at their interface. The highly soft PU@ Ag fibers were fully spooled within the droplet and reversibly uncoiled when a tensile force was applied. Without mechanical failures of the Ag sheaths, an excellent conductivity of 3.9 × 10 4 S cm −1 was retained at a strain of 1200% for 1000 spooling−uncoiling cycles. A light-emitting diode connected to a multiarray of droplet−PU@Ag fibers exhibited stable operation during spooling− uncoiling cycles.

Semiconducting polymers are considered essential materials because of the dramatically increasing demand for deformable electronic and energy devices. However, an improvement in both the electrical conductivity and mechanical stretchability of these polymers has been challenging. In this study, we designed a composite material comprising Li-complexed poly­(3-hexylthiophene) nanofibrils (Li-P3HT) and poly­(styrene-b-butadiene-b-styrene) (SBS) as the conductive and stretchable active layers of electronic skins (e-skins). The cooling process of a P3HT/SBS solution leads to the one-dimensional growth of P3HT crystals due to strong π–π interactions between the thiophene backbones, which assists in the formation of percolation networks within the SBS matrix after spin coating. The complexation of Li+ and thiophene backbones significantly increased the hole concentration of the nanocomposites. The resulting conductivity was found to be 1.27 × 10–3 S cm–1, which is 5.7 times higher than that of pristine P3HT/SBS. Furthermore, the stretchable SBS matrix led to an excellent retention of long electrical pathways via percolated Li-P3HT nanofibrils for a strain of up to 50%. The printed Li-P3HT/SBS arrays on Ag nanowire/Ecoflex stretchable electrodes were utilized as the active layers of high-performance strain and pulse sensors.