Carbon-sandwiched perovskite solar cell

Promising perovskite solar cell technology with soaring power conversion efficiencies has the common problems of low stability and high cost. This work provides a solution to these problems by employing a carbon sandwich structure, in which the fullerene bottom layer solves the stability issue and the carbon nanotube top electrode layer offers the merits of having high stability and being low-cost. Devices fabricated using different hole-transporting materials infiltrated into carbon nanotube networks were examined for their performance and stability under constant illumination in air. Polymeric hole-transporting layers show much higher stability when combined with carbon nanotubes due to their compact nature and stronger interaction with the carbon network. As a result, the encapsulated device showed high stability both in air and under light illumination, maintaining up to 80% of the initial efficiency after 2200 hours under actual operation conditions. Cost analysis also shows that using the polymeric hole-transporting materials in carbon nanotube films brings the fabrication cost down to less than 5.5% that of conventional devices. Our study proposes a promising cell structure toward highly stable and low-cost perovskite photovoltaic technologies for the future.