Synergistic effect of In2O3 nanocuboids and TiO2 nanocubes in electron transport bilayer for carbon-based perovskite solar cells

Abstract

Bilayer-based electron transport layers (ETLs) are recently emerging due to their benefits in the efficient charge carrier extraction and transportation with diminished interfacial recombination loss. Here, the carbon electrode-based perovskite solar cells (C–PSCs) with mesoscopic bilayer-oriented ETLs using In2O3 nanocuboids and varied concentrations of TiO2 nanocubes were fabricated and their performances were evaluated. In2O3 nanocuboids and TiO2 nanocubes were synthesized through hydro and solvothermal routes respectively. The synthesized samples' structural, morphological, and optical behaviours were characterized by PXRD, FESEM, HRTEM and UV–Vis spectroscopy. With pertinent studies, the impact of all the variants of bilayer-based ETLs on the formation of the perovskite layer was thoroughly investigated. The device based on monolayer ETL has achieved power conversion efficiency (PCE) of 6.9 % with current density (Jsc) of 18.69 mA/cm2. The highest PCE of 10.7 % with Jsc of 22.15 mA/cm2 was achieved for the champion device with the optimized bilayer of In2O3/TiO2 (200 mg/ml). This champion device showed ambient stability (at 35 °C with ∼70 % humidity) of 83 % from its initial PCE for 35 days without any encapsulation. Thus, the suitable morphology of the bilayer-based ETL facilitated the interface passivation by the self-embedding process, which played a significant role in the improvement of the cell performance.