Efficient, stable, and fully printed carbon-electrode perovskite solar cells enabled by hole-transporting bilayers

Printable planar carbon electrodes emerge as a promising replacement for thermally evaporated metals as the rear contact for perovskite solar cells (PSCs). However, the power conversion efficiencies (PCEs) of the state-of-the-art carbon-electrode PSC (c-PSC) noticeably lag behind their metal-electrode counterparts. Here, we propose a hole-transporting bilayer (HTbL) configuration to improve the fill factor and the open-circuit voltage of c-PSCs simultaneously. The HTbL is prepared by sequentially blade coating two organic semiconductors between perovskite and carbon, with the outer HTL enhancing hole extraction to carbon, while the inner HTL mitigates perovskite surface recombination. Consequently, our fully printed c-PSCs with HTbL outperform those with single HTL, and a stabilized champion PCE of 19.2% is achieved compared with that of 17.3%. Our prototype c-PSC stably operates during 1 sun, 65 & DEG;C aging test (ISOS-L-2I) for 2,500 h showing negligible PCE drop, validating its potential as a highly cost-effective photovoltaic technology.

Automated summary

Printable planar carbon electrodes are found to be a promising alternative to thermally evaporated metals as the rear contact for perovskite solar cells (PSCs). However, the power conversion efficiencies (PCEs) of carbon-electrode PSCs lag behind metal-electrode PSCs. In this study, a hole-transporting bilayer (HTbL) configuration is proposed to simultaneously improve the fill factor and open-circuit voltage of carbon-electrode PSCs, leading to a significantly higher PCE of 19.2% compared to 17.3%. This research demonstrates the potential of fully printed carbon-electrode PSCs with HTbLs as a highly cost-effective photovoltaic technology.