Effect of annealing temperature on the performance of printable carbon electrodes for perovskite solar cells

Abstract

Perovskite solar cells (PSCs) with mesoporous TiO2 electron transport layers have reached >22% efficiency at laboratory scale (<1 cm2), however, these layers are fabricated using spin-coating, which is not conducive to large-scale or high throughput fabrication. Alternatively, screen printing, slot die coating and spray pyrolysis techniques are very suitable for commercial scale production of PSCs. In this work, low-cost carbon films intended for PSCP top conductor layer have been prepared by screen printing method and their electrical, morphological and structural properties have been investigated for annealing temperatures ranging from 100 C to 400 C. The properties of the carbon films have been examined using scanning electron microscopy, atomic force microscopy, sheet resistance measurement technique, thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy and raman spectroscopy. The carbon films annealed at 250 C-300 C exhibited good electrical and morphological properties, however, annealing temperature over 300 C deforms and peels off the carbon films. Nevertheless, devices fabricated from printed substrates with a carbon top contact showed that annealing of the hole transport material-free mesoscopic architecture to over 300 C is necessary prior to the infiltration of the perovskite precursor solution. Although a low annealing temperature is required for better adherence of the conductive carbon films, however, temperatures higher than 300 C are needed to fabricate mesoscopic perovskite solar cells.