Delafossite materials (CuIMIIIO2) are p-type metal oxides which can be used as hole transport layers in a wide range of heterojunction solar cells. These materials are interesting because of their crystal structure that can facilitate hole diffusion through the valance band. Maximizing the interfacial capacitance within porous nanocrystalline films of CuGaO2 is a primary goal for enhancing their performance in solar cells. The electrochemistry of CuGaO2 can reveal much information about the capacitance of the material and therefore the electronic density of valance band states. Here we have investigated the structural and electrochemical properties of CuGaO2 nanocrystalline thin films in acetonitrile solution with LiClO4 electrolyte. Nanocrystalline films are produced by dispersion of CuGaO2 nanocrystals in a polymer solution designed to control the porosity of the resulting film. We have used two different chain lengths of ethyl cellulose polymers (10 cps and 22 cps) to understand their impact on film morphology. As the film capacitance is related to surface area, a more porous film is expected to increase the film capacitance. In addition, we have also varied the CuGaO2 : polymer ratio to find the optimum condition for enhanced film capacitance. Keeping CuGaO2 : polymer ratio constant (1:1) we have changed percent weight of CuGaO2 (15%, 12%, 10%, 8%, 6%) to find the best quality film by spin coating. The films were characterized by powder XRD where peak ratios for (003)/(006) and (012)/(006) planes were calculated to understand the orientation of nanocrystals within the film. Electrochemical Impedance Spectroscopy (EIS) was used to probe the electrochemical behavior and capacitance of the films. We are particularly observing the Creal values at low frequency for comparative study of various films. These studies find that Creal is maximized for 1:1 ratio of CuGaO2 : polymer mixture.

Impact of ethyl cellulose on the porosity and capacitance of CuGaO2 mesoporous nanocrystalline thin films

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.