Improving the charge carrier separation efficiency at the perovskite/carbon electrode interface in HTL-free carbon-based perovskite solar cells via physical polishing

Abstract

Carbon-based perovskite solar cells (C-PSC) are favored by researchers for their low cost and support for large-scale production. However, the particles precipitated on the surface of the perovskite (PVK) film can affect the fabrication and operation of C-PSC, such as disrupting the coating of C electrode film and producing defects that can aggravate the carrier recombination. Herein a reliable and efficient C-PSC is prepared by applying a physical polishing strategy. The compact interface contact and the larger Fermi level difference at the carbon-perovskite (C/PVK) interface are achieved, resulting in a 21.4% increase in power conversion efficiency compared to that without polishing. A hole-transport-layer-free C-PSC with an efficiency of 12.2% is achieved, resulting from the reduction of perovskite surface roughness and defects that cause non-radiative recombination. It is revealed that the physical polishing can reduce the root mean square roughness from 15.9 nm to 1.2 nm, facilitating the screen printing of the C electrode. The carrier lifetime of the perovskite film also increases from 39.9 ns to 73.3 ns, which improves the photocurrent of the solar cell. We believe that the improved C/PVK interface contact will provide a solid foundation for the future large-scale commercial production of perovskite solar cells.

Advances in the research of carbon electrodes for perovskite solar cells

“…39–46 Furthermore, adjusting the film formation temperature and carbon layer thickness enhances carrier transport between the perovskite and carbon. 47–50 In 2013, Ku et al 51 proposed the utilization of carbon black/spheroidal graphite as electrodes, replacing noble metal materials in PSCs. The resulting photovoltaic device achieved a PCE of 6.64%.…”