Polymer‐Based Anti‐Solvent Engineering to Fabricate Stable and Efficient Triple‐Cation Perovskite Solar Cells

Perovskite materials, due to their excellent photovoltaic features, have aroused the researchers ' admiration as a photon-absorption film for the next-generation photovoltaics. The interface tailoring of perovskites and hole-transport layer (HTL) is one of the critical approaches to achieve effective and stabilized perovskite solar cell (PSC). Hence, poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b ']dithiophene-2,6-diyl][3-fluoro-2-[(2 ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) as a polymeric organic semiconductors was employed for doping of anti-solvent solution to modify the perovskite film. Results showed with PTB7 dopant; grain boundaries (GBs) of the perovskites are reduced. It suppressed carriers ' trap centers in the perovskite film and decreased recombination processes within perovskite layers. Besides, the high intrinsic conductivity of PTB7 material assisted charge injection at the perovskites/HTL interfaces and hindered carrier's accumulation. The device with PTB7 showed a more matched energy level and a higher prevention for recombination than the device without PTB7 dopant, which are reasons for the considerable boost in the open-circuit voltage (V-OC) and fill-factor (FF), giving rise a power conversion efficiency (PCE) of 19.18 % for the champion performing PVs. Most important, the hydrophobic origin of PTB7 leads to superb humidity stability in the device with PTB7 dopant with 85 % of the original performance remaining after more than 800 h storing in air with similar to 40 % RH.