A morphological study of bicontinuous concentric lamellar silica synthesized at atmospheric pressure and its application as an internal micro-reflector in dye-sensitized solar cells

Abstract

KCC-1, a nanostructured silica material with a bicontinuous concentric lamellar (bcl) morphology, provides plenty of functional characteristics, such as an open channel structure, excellent accessibility, and a large surface area. Although bcl silica exhibits various superior properties, studies on its morphology and its application in dye-sensitized solar cells (DSSCs) are still limited. Therefore, this work aims to study the influence of the synthesis time on the morphology of bcl silica. Moreover, we used the synthesized bcl silica as internal micro-reflectors in DSSCs. The bcl silica was synthesized using the reflux method by varying synthesis times. The morphology of bcl silica was observed using FESEM and HRTEM. FESEM images show that bcl silica has bicontinuous lamellar walls arranged concentrically to form spherical particles. As the synthesis time increases, the average particle size of bcl silica increases. The quantization of bcl silica binary images shows that the average lamellar cross-sectional area ratio decreases with increasing synthesis time. The simulation of the Cahn–Hilliard's spinodal decomposition model using MATLAB also describes the lamellar cross-sectional area ratio of bcl silica. In addition, to characterize the FESEM image's texture, a Shannon entropy calculation was performed. The line and circular gray value intensity profiles of the HRTEM image show that bcl silica has a denser core than the outer part. The denser core proves that the lamellae in bcl silica are concentrically arranged towards the particle core. Furthermore, we added bcl silica to a photoanode to see the effect of bcl characteristics on the DSSC performance. The results show that the bcl silica significantly improves the light-harvesting efficiency in DSSCs due to its low refractive index and open channel structure.