Ion-Organic Compound Interface Strategy Enables High-Efficiency Perovskite Solar Cells

Abstract

The interface strategy plays an irreplaceable role in improving the photovoltaic performance of perovskite solar cells (PSCs). To alleviate this issue, we apply tetrabutylammonium hexafluorophosphate (TBAPF 6 ), an ion-organic compound, to modify the perovskite/Spiro-OMeTAD interface of the n−i−p structure. TBAPF 6 effectively improves carrier transport at interfaces by simultaneously interacting with Pb 2+ and I − vacancy electrostatics, and PF 6− and TBA + have electrostatic interactions with the I − and Pb 2+ vacancies, respectively. Moreover, TBAPF 6 can strongly penetrate the SnO 2 surface, forming P−O−Sn to reduce the −OH suspension bond on the SnO 2 surface. Due to the formation of N−H−F hydrogen bonds, the transition of α-FAPbI 3 to δ-FAPbI 3 can be inhibited. The multiple fluorine atoms and butyl chains of TBAPF 6 efficiently result in improved hydrophobicity of the perovskite film. With the addition of TBAPF 6 , energy-level matching and mechanical adhesion at the perovskite and Spiro-OMeTAD interfaces can be enhanced simultaneously. As a result, we achieved a target champion power conversion efficiency (PCE) of 23.88%, with an excellent short-circuit current density (J SC ) of 25.90 mA cm −2 , versus 20.94% in the control device. The unencapsulated device with TBAPF 6 treatment exhibits a high PCE retention of 84.5% when stored under a controlled environment (relative humidity of 30% and room temperature) for 1000 h. Our results demonstrate that TBAPF 6 is an efficient dual-function modifier for constructing high-performing PSCs.