Metalloligand Nickel Bis(Dithiolene) Based Metal–Organic Frameworks for Efficient Photocurrent and Photothermal Conversion

Nickel bis(dithiolene) complexes
are strong sunlight absorbers
with high thermal- and photostability and are nonluminescent, resulting
in remarkable photothermal properties. Nevertheless, nickel-bis(dithiolene)-based
metal–organic frameworks (MOFs) have rarely been reported as
photothermal and photocurrent agents. Herein, nickel-bis(dithiolene-dibenzoic
acid) [Ni(C2S2(C6H4COOH)2)2], as a new functional redox-reversible “non-innocent”
metalloligand, was innovatively assembled into two MOFs, [Zn2{Ni(C2S2(C6H4COO)2)2}(H2O)2]·2DMF and
[Cd2{Ni(C2S2(C6H4COO)2)2}(H2O)2]·2DMF
(1 and 2, DMF = N,N-dimethylformamide). Under one-sun illumination (0.1 W
cm–2, 300–2500 nm), the temperature of the
MOFs sharply increased to 69.6 and 69.3 °C from room temperature
in 300 s, concomitant with induced photocurrents of 7.0 and 6.5 μA
for 1 and 2. The considerable performance
is due to charge transfer, as revealed by cyclic voltammetry (CV)
and solid-state UV/vis–NIR spectroscopy. This study not only
provides insights into the development of photothermal and photoconductivity
materials but also paves the way for designing functional materials
with appealing applications.