Improving ionic thermoelectrics: Using ions as charge carriers in thermoelectric devices usually requires using either thermal diffusion or redox reactions at two electrodes with different temperatures. Han et al. leveraged both of these strategies to develop a gelatin-based ionic thermoelectric device that uses alkali salts and an iron-based redox couple to generate a large thermopower. This device is capable of generating useful amounts of energy from body heat. Science , this issue p. 1091

Indoor photovoltaics are promising to enable self‐powered electronic devices for the Internet of Things. Here, reported is a triple‐anion CH₃NH₃PbI_2−xBrCl_x perovskite film, of which the bandgap is specially designed for indoor light harvesting to achieve a record high efficiency of 36.2% with distinctive high open circuit voltage (V_oc) of 1.028 V under standard 1000 lux fluorescent light. The involvement of both bromide and chloride suppresses the trap‐states and nonradiative recombination loss, exhibiting a remarkable ideality factor of 1.097. The introduction of chloride successfully restrains the halide segregation of iodide and bromide, stabilizing the triple‐anion perovskite film. The devices show an excellent long‐term performance, sustaining over 95% of original efficiency under continuous light soaking over 2000 h. These findings show the importance and potential of I/Br/Cl triple‐anion perovskite with tailored bandgap and suppressed trap‐states in stable and efficient indoor light recycling.

Flexible triboelectric nanogenerators (TENGs) have attracted increasing interest since their advent in 2012. In comparison with other flexible electrodes, hydrogels possess transparency, stretchability, biocompatibility, and tunable ionic conductivity, which together provide great potential as current collectors in TENGs for wearable applications. The development of hydrogel‐based TENGs (H‐TENGs) is currently a burgeoning field but research efforts have lagged behind those of other common flexible TENGs. In order to spur research and development of this important area, a comprehensive review that summarizes recent advances and challenges of H‐TENGs will be very useful to researchers and engineers in this emerging field. Herein, the advantages and types of hydrogels as soft ionic conductors in TENGs are presented, followed by detailed descriptions of the advanced functions, enhanced output performance, as well as flexible and wearable applications of H‐TENGs. Finally, the challenges and prospects of H‐TENGs are discussed.

Hydrovoltaic technologies have been proposed in recent years to generate electricity by virtue of water interacting with nanostructured materials, such as monolayer graphene and graphene derivatives, as promising renewable energy alternatives. In particular, moisture flow, with natural abundance in daily life, contains tremendous energy but remains unutilized. Here, we invented a new hydrovoltaic device comprising the ionic polymer Nafion and poly(N-isopropylacrylamide) hydrogel, by which an ultrahigh voltage of −1.86 V was reached using one single module in a sustainable manner and its fast voltage response is significantly distinguished from all moisture-enabled electric generators. Our device not only outperforms in power density but also the adaptability to moisture flow and the simplicity of the device, enabling energy recovery in various real-life scenarios from human breath to mechanical water spray and even water-cooling processes. Its practical significance as a portable power supply was demonstrated by charging capacitors and powering electrochromic smart windows without any auxiliary rectifying and amplifying circuits.