Near‐infrared (NIR) light‐driven bilayer actuators capable of fast, highly efficient, and reversible bending/unbending motions toward periodic NIR light irradiation are fabricated by exploiting the photothermal conversion and humidity‐sensitive properties of polydopamine‐modified reduced graphene oxide (PDA‐RGO). The bilayer actuator comprises a PDA‐RGO layer prepared by a filtration method, and this layer is subsequently spin‐coated with a layer of UV‐cured Norland Optical Adhesive (NOA)‐63. Given the hydrophilicity of PDA, the PDA‐RGO layer can absorb water to swell and lose water to shrink. The intrinsic NIR absorbance of RGO sheets convertes NIR light into thermal energy, which transfers the humidity‐responsive PDA‐RGO layer to be NIR light‐responsive. Considering that the shape of the NOA‐63 layer remains unchanged under NIR light, periodic NIR light irradiation leads to asymmetric shrinkage/expansion of the bilayer, which enables fast and reversible bending/unbending motions of the bilayer actuator. We demonstrate that compared with a poly(ethylenimine)‐modified graphene oxide layer, the PDA‐RGO layer is unique in fabricating highly efficient bilayer actuators. A NIR light‐driven walking device capable of performing quick worm‐like motion on a ratchet substrate is built by connecting two polyethylene terephthalate plates as claws on opposite ends of the PDA‐RGO/NOA‐63 bilayer actuator.

Recently, owing to the great structural tunability, excellent photothermal property, and strong photobleaching resistance, organic-small-molecule photothermal materials are proposed as promising solar absorbent materials. Herein, through fusing two strong electron-withdrawing units dibenzo[f,h]quinoxaline and anthraquinone units, a rigid planar acceptor dibenzo[a,c]naphtho[2,3-h] phenazine-8,13-dione (PDN) with stronger electron-withdrawing ability is obtained and used to construct donor-acceptor-type organic-small-molecule solar-energyabsorbing material, 2,17-bis(diphenylamino)dibenzo[a,c]naphtho[2,3-h]phenazine-8,13-dione (DDPA-PDN). The new compound exhibits a strong intramolecular charge transfer character and conjugates rigid plane skeleton, endowing it with a broadband optical absorption from 300 to 850 nm in the solid state, favorable photothermal properties, high photothermal conversion ability, and good photobleaching resistance. Under laser irradiation at 655 nm, the solid photothermal conversion efficiency of the resulting DDPA-PDN molecule reaches 56.23%. Additionally, DDPA-PDN-loaded cellulose papers equipped with abundant microchannels for water flow are integrated with thermoelectric devices, thus achieving an evaporation rate and voltage as high as 1.07 kg m −2 h −1 and 83 mV under 1 kW m −2 solar irradiation, respectively. This study demonstrates the application of photothermal organic-small-molecules in water evaporation and power generation, therefore offering a valuable prospect of their utilization in solar energy harvesting.

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