Broadband-absorbing structurally distorted cocrystal with enhanced nonradiative decay for solar interfacial water evaporation

Abstract

Organic cocrystals have become increasingly prevalent in a variety of research domains, owing to the simple preparation, cost-effectiveness, and highly tunable properties. Particularly, the strong charge transfer (CT) interactions in cocrystals render them promising candidates for high-efficiency photothermal conversion materials. However, the majority of reported organic photothermal cocrystals exhibit planar and rigid π-conjugated structures, which restrict molecular vibrations while simultaneously impeding non-radiative dissipation processes—ultimately hindering the enhancement of photothermal conversion performance. Herein, we design a novel non-planar photothermal NMTQ cocrystal, which shows a broadband absorption range of 220–2000 nm and high photothermal conversion efficiencies from ultraviolet (UV) to near-infrared (NIR)-II region. Quantum chemical calculations have been utilized to demonstrate that the distorted butterfly-like conformation in NMTQ is conducive to non-radiative transitions via higher non-adiabatic couplings (NACs) and lower spatial overlap integral (S_r). An interfacial solar evaporation system was constructed using NMTQ cocrystals, achieving an evaporation rate of 2.158 kg m⁻² h⁻¹ with 94.96% solar-to-vapor conversion efficiency under 1 Sun irradiation. The photothermal platform demonstrated simultaneous contaminant removal functionality, establishing a sustainable strategy for clean water production through rational photothermal material design.