Ultrastable NIR Absorbing Imidazole‐Based Open‐Shell Diradicaloids for High‐Efficiency Photothermal Steam and Power Generation

Open‐shell diradicaloids are promising photothermal materials owing to their near‐infrared absorption and efficient non‐radiative energy dissipation. However, complex synthesis and inherent reactivity make them less relevant for practical applications. Herein, we report a stable, synthetically readily accessible pyrene‐integrated imidazole‐based open‐shell diradical ( PBQ ) photothermal material. PBQ possesses a high diradical character, with a low Δ E S‐T of −2.8 kcal/mol, and strong solid‐state absorption extending to ∼1600 nm. Under one‐sun illumination for 10 min, PBQ attains a surface temperature of 71°C and exhibits high photothermal solar steam generation of 2.05 kg m − 2 h − 1 with a solar‐to‐vapour conversion efficiency of 98%. Notably, PBQ outperforms previously reported diradicaloid‐based photothermal materials. PBQ exhibits excellent chemical‐ and photo‐stability even after 40 days of water soaking and 14 days under natural sunlight, or under high‐light intensity up to 2 suns for 120 mins. The high stability of PBQ is attributed to extensive delocalisation of the spin density across its large π‐conjugated backbone and the presence of stabilising heteroatoms. Additionally, PBQ exhibits photothermal power generation and simultaneous cogeneration of steam and electricity. This work demonstrates an imidazole‐linked diradicaloid as a high‐performance photothermal material, offering a molecular platform for solar‐driven water purification and energy conversion.