Ultra-low-cost all-air processed carbon-based perovskite solar cells from bottom electrode to counter electrode

Despite impressive power conversion efficiency (PCE) climbing up to 25.2%, complex processing and high cost of perovskite solar cells (PSCs) associated with hole transport material (HTM), Au counter electrode and trans-parent conducting oxide (TCO) electrode limit the commercial applications of PSCs. We herein fabricate an ultra low-cost HTM-free C-PSC with the structure of AgNWs-graphene (AgNWs-G)/SnO2/perovskite/carbon by using 1D-2D hybrid AgNWs-G transparent electrode instead of conventional ITO electrode. The optimized AgNWs-G film (AgNWs-G-2 film) with a relatively high transmittance (similar to 86%) achieves a sheet resistance (Rs) of 11.0 Omega sq(-1) lower than that of ITO (13.5 Omega sq(-1)). Compared with AgNWs film, the AgNWs-G-2 film exhibits fantastic stability of Rs within the entire duration of air exposure, even though at high temperatures or continuous illumination. Such the low-cost AgNWs-G based C-PSC achieves an outstanding PCE of 15.31% and a long-term stability of 87.5% for 60 days in air conditions. It is worth noting that all preparing processes from bottom electrode to counter electrode in the total PSC device are operated in actual ambient air condition, and the annealing temperature for each functional layer is no more than 150 degrees C, hence leading to the construction of ultra-low-cost PSCs.