Preparation of ultrathin Cu₃ (BTC) ₂ film by heat treatment of layer-by-layer deposition

Based on layer-by-layer deposition, heat treatment was introduced to prepare continuous and defect-free Cu₃ (BTC)₂ film on glass substrate. The effects of some parameters including heat treatment temperature, assembly time and solvent were investigated with field emission scanning electron microscopy (FESEM). The results showed that film thickness was only about 200 nm which was much thinner than those previously reported. Heat treatment was fantastically beneficial for high crystallinity Cu₃ (BTC)₂ film formation and no crack was found in the film even at a high heat treatment temperature. At the assembly time about 5 min or 10 min, small crystal particles with uniform size were obtained. However, at a longer assembly time of 20 min, particle size became non-uniform, leading to film unevenness. Moreover, by changing the assembly solvent environment, films with different dimensions were formed.