Structure Engineering of Hole–Conductor Free Perovskite-Based Solar Cells with Low-Temperature-Processed Commercial Carbon Paste As Cathode

Low-temperature-processed (100 °C) carbon paste was developed as counter electrode material in hole–conductor free perovskite/TiO2 heterojunction solar cells to substitute noble metallic materials. Under optimized conditions, an impressive PCE value of 8.31% has been achieved with this carbon counter electrode fabricated by doctor-blading technique. Electrochemical impedance spectroscopy demonstrates good charge transport characteristics of low-temperature-processed carbon counter electrode. Moreover, this carbon counter electrode-based perovskite solar cell exhibits good stability over 800 h.