Owing to their unique ability to assemble and organize redox- and photoactive building blocks and guest molecules in a highly ordered fashion, crystalline porous metal-organic frameworks (MOFs) can perform myriad complex functions, including charge conduction and light to electrical energy conversion. Taking full advantage of the light-harvesting capacity of chromophoric MOFs in photovoltaic devices requires robust, uniform, precisely oriented MOF films directly attached to suitable electrodes that can promote charge separation, diffusion, and injection upon photosensitization. Herein, we demonstrate spontaneous solvothermal growth of predominantly [100]-oriented, robust, uniform pillared porphyrin framework-11. When introduced as photoanodes in liquid-junction solar cells, the [100]-oriented PPF-11 films display excellent photovoltaic response (JSC: 4.65 mA/cm2, VOC: 470 mV, photocurrent efficiency (PCE): 0.86%) and relatively small photoanode/electrolyte interfacial charge-transfer resistance (259 Ohm) under 1-sun illumination, easily outperforming control devices (PCE ≤ 0.2%) and all intrinsically light-harvesting 3D porous MOFs reported to date by quite wide margins. The non-catenated porous PPF-11 was also able to accommodate electron deficient large C60 guests, filling nearly half of its cavities upon saturation. Despite experiencing significant ZnTCPP/C60 charge transfer interaction, the C60-doped PPF-11 films displayed much weaker photovoltaic response to undoped PPF-11 films, possibly due to exclusion of I–/I3– electrolytes from the C60-occupied cavities and the inability of isolated C60 guests to support long-range charge movement.

Efficient MOF-sensitized solar cells made of [100]-oriented pillared porphyrin framework films

2019 Spring National Meeting

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