Cooperative Crystallization of Chiral Heterometallic Indium(III)–Potassium(I) Metal–Organic Frameworks as Photosensitizers in Luminescence Sensors and Dye-Sensitized Solar Cells

In this work, the coexistence of In(III) and K(I) induces a rapid crystal growth of single crystals of heterometallic metal–organic frameworks (MOFs), [In 0.5 K(3-qlc)Cl 1.5 (H 2 O) 0.5 ] 2 n ( 1 ) and [InK(ox) 2 (H 2 O) 4 ] n ( 2 ) (3-Hqlc = quinoline-3-carboxylic acid; H 2 ox = oxalic acid). Remarkably, with the help of achiral 3-Hqlc, compound 1 represents the chiral interpenetrating p-block heterometallic MOFs with helical chain along the 4 3 screw axis, while compound 2 possesses a highly symmetric (4,4,4)-connected topology network with a Schläfli symbol of (4 2 ·8 3 ·10)(4 2 ·8 4 ). Consideration of two different organic ligands viz. 3-Hqlc and H 2 ox constructed heterometallic MOFs with different geometrical dimensions of unit cells, their influences on luminescence and photovoltaic properties are studied. Compounds 1 and 2 show tunable luminescence from blue to yellow and white by varying the temperature in the solid state. Encouraged by the UV–visible absorption and HOMO–LUMO energy states matched for sensitizing TiO 2, the two compounds are employed in combination with N719 in dye-sensitized solar cells (DSSCs) to compensate for absorption in the region of ultraviolet and blue-violet. Under optimized conditions, the DSSCs devices using cosensitizers of 1 /N719 and 2 /N719 display an overall conversion efficiency of 8.07% and 7.42%, which is 22.09% and 12.25% higher than that of a device solely sensitized by N719 (6.61%). Consequently, both of the two compounds could serve as excellent photosensitizers and application in luminescence sensors and DSSCs.