Solid-State Thermolysis of Anion Induced Metal–Organic Frameworks to ZnO Microparticles with Predefined Morphologies: Facile Synthesis and Solar Cell Studies

Abstract

Simple one-step solid state thermolysis of two Zn-based homochiral metal organic frameworks (MOFs) leads to a dramatic difference in morphologies which depends on the anion (-Cl and -Br) and calcination environment (air and N2). Rod-shaped (aspect ratio ∼ 20), hexagonal column shaped (aspect ratio ∼ 3), and elliptical aggregation of ZnO morphologies (aspect ratio ∼ 3) are obtained and characterized. Although these two MOFs possess similar rod-shaped morphology, they produce dramatic change in resulting ZnO microparticle morphologies (from rod-shaped ZnO microparticles in the case of thermolysis of MOF 1 to hexagonal column shaped ZnO microparticles in the case of MOF 2 thermolysis) when calcined in N2 at 800 °C. However, when we calcined both MOF 1 and 2 in air, we encountered similar elliptical aggregation of ZnO microparticles. These ZnO microparticles show permanent porosity, visible light emission centered at 605 or 510 nm. Moreover, they show 0.15% and 0.14% dye sensitized solar cell activity. To the best of our knowledge, this is the first report of dye sensitized solar cell activity of ZnO microparticles obtained from one-step thermolysis of porous homochiral MOFs.