Tian Du, Hakan U. Dag, Zijian Peng, Jonas Englhard, Anastasia Barabash, Handan Zhang, Jiyun Zhang, Jiayi Tan, Shudi Qiu, Lirong Dong, Michael J. Wagner, Jens Hauch, Fei Guo, Olga Kasian, Julien Bachmann, Christoph J. Brabec
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.