Hydrophobic π-conjugated organic small molecule as a multi-functional interface material enables efficient and stable perovskite solar cells

Surface treatment of perovskite films with interface materials is an effective strategy to resolve trap-mediated nonradiative recombination toward high efficiency and stability of perovskite solar cells (PSCs). However, interface materials for multi-functional treatment have been rarely investigated in PSCs. In this work, a novel pyrene-based organic material (TAAPyr) is first introduced as a defect passivation layer and a protect layer against moisture for PSCs application. With the TAAPyr interfacial modification, both perovskite surface defects and nonradiative recombination are effectively decreased as well as the carrier transport in device is also enhanced, As a consequence, the best power conversion efficiencies (PCE) up to 22.45% for TAAPyr-based device was obtained, clearly outperforming the control one (20.37%). Moreover, it was found that the pi-conjugated TAAPyr can promote intermolecular face-to-face stacking on the surface perovskite film, which is favorable to making the perovskite surface more hydrophobic and consequently enhance PSCs long-term stability. The unencapsulated PSCs can retain 92% of the initial PCE after storage for 600 h at similar to 65% RH, in comparison with 64% efficiency retention of the device without TAAPyr under the same conditions. This work presents a new strategy to enhance the efficiency and stability of PSCs by multi-functional pi-conjugated passivator.

Automated summary

The novel pyrene-based organic material TAAPyr is introduced as a defect passivation layer and a protect layer against moisture for perovskite solar cells (PSCs) application, effectively decreasing surface defects and nonradiative recombination while enhancing carrier transport and power conversion efficiencies. The multi-functional pi-conjugated passivator TAAPyr shows potential in improving efficiency and stability of PSCs by promoting intermolecular face-to-face stacking and making the perovskite surface more hydrophobic.