Enhancing the viability of p-i-n perovskite solar cells with printable carbon cathode: Origin of polarity inversion

Printable rear electrodes represent a key enabling technology for the upscaling of perovskite solar cells (PSCs). Carbon electrodes are appealing candidates widely employed in n-i-p (so-called "conventional") architectures, but their integration into p-i-n (so-called "inverted") architectures is prohibited by interfacial energetic mismatch. We address this challenge by introducing a tin oxide (SnO x ) interlayer with desirable mechanical durability and n-doping level. We show in detail how the tailored interlayer converts carbon from a hole-collecting anode to an electron-collecting cathode and how the electron-extraction barrier is minimized, narrowing the efficiency gap between carbon (21.8%) and silver (24.0%) electrodes. The advancement results in a remarkably improved viability of the PSCs: a modest drop in efficiency is outweighed by a 3-fold improvement in projected operational lifetime (>8,000 h) and a 60% reduction in the bill of materials. These results underscore the potential of carbon as a cost-effective alternative to silver in the industrialization of p-i-n PSCs.