Organic Dye-Modified Two-Dimensional Metal–Organic Framework/Carbon Nanotube Composite Films for Photothermoelectric Applications

Photothermoelectric (PTE) systems, which convert light into electricity through sequential photothermal (PT) and thermoelectric (TE) processes, offer a promising strategy for self-powered wearable electronics. In this work, we develop a homogeneous PTE composite system by integrating carbon nanotubes (CNTs) with a dye-modified two-dimensional metal-organic framework (2D MOF), referred to as ZrBTBD, obtained via the postsynthetic modification of a 2D MOF, ZrBTB, with N719 dye. The introduction of N719 enhances visible-light absorption and facilitates doping level modulation with CNTs. Together with n-type doping using N-DMBI, the resulting p-type C/ZrBTBD10 and n-type C/ZrBTBD-N5 composites achieve high power factors of 465.7 and 363.1 μW m⁻¹ K⁻², respectively. Under 100 mW cm⁻² illumination, the PT temperature increases from 47.3 °C to 51.2 °C, and the zT is significantly enhanced compared to CNTs. A flexible PTE generator assembled from these composites delivers an open-circuit voltage of 12.3 mV and a maximum power output of 365.4 nW. A wearable prototype demonstrates its potential for flexible, self-powered electronics. This work represents the demonstration of dye-immobilized MOF/CNT composite materials in PTE systems, offering a molecular-level strategy for integrating light harvesting, interfacial charge modulation, and thermoelectric conversion.