Core-Twisted Tetrachloroperylenediimides: Low-Cost and Efficient Non-Fullerene Organic Electron-Transporting...

Herein, core-twisted tetrachloroperylenediimides (ClPDIs) were introduced as new efficient electron-transporting materials (ETMs) to replace the commonly used fullerene acceptor PC₆₁ BM in inverted planar perovskite solar cells (PSCs). ClPDI showed a low-lying lowest unoccupied molecular orbital (LUMO) energy level of -3.95 eV, which was compatible with the conduction band of CH₃ NH₃ PbI_3-x Cl_x (-3.90 eV). In addition, the role of the length of the alkyl side chain at the imide position of ClPDI in modulating the molecular solubility, aggregation capacity for charge-transport properties, surface hydrophobicity, and PSC performance was investigated. The device based on ClPDI-C4 (ClPDI with n-butyl side chains) as ETM achieved a maximum power conversion efficiency (PCE) of 17.3 % under standard AM 1.5G illumination, which iwas very competitive with that of the reference device employing PC₆₁ BM/C₆₀ (PCE=17.2 %) as ETM. Moreover, the devices with ClPDIs as ETMs exhibited better device stability than that with PC₆₁ BM/C₆₀ . This work highlights the great potential of ClPDI derivatives as low-cost (≈2.0 USD g^-1 ) and effective ETMs to obtain efficient solution-processed inverted PSCs. This class of ClPDI derivatives is expected further promote the performance and stability of PSCs after extended investigation.