Cost-Optimized Perovskite Solar Cells Enabled by Molecularly Engineered Hole Transport

Commercial deployment of perovskite solar cells is still hampered by the high price of the conventional hole transport material spiro-OMeTAD and the Au rear electrode used in state-of-the-art n–i–p devices. Here, we demonstrate that judicious management of hole transport simultaneously reduces material costs and pushes device efficiency to a record value of 25.03% (certified 24.44%) for Cu-electrode-based n–i–p perovskite solar cells. Diluting the pristine spiro-OMeTAD precursor 4-fold with a volatile cosolvent preserves film morphology and electronic properties while reducing the consumption of a costly organic semiconductor. We further introduce a solution-processed proton-coupled electron-transfer strategy to in situ create a p–p + homojunction hole transport layer, which helps build up an Ohmic contact with a low-cost Cu rear electrode and accelerates hole extraction. Replacing Au with Cu lowers the electrode cost by more than 4 orders of magnitude without compromising stability: unencapsulated cells retain 93% of their initial efficiency after 700 h of operation under continuous illumination. Our results demonstrate a practical pathway to economically viable, high-performance perovskite solar cells and advance the prospects for commercial manufacturing.