Regulation interfacial energy by reducing the Young’s modulus of perovskite film in carbon-based HTM free MAPbI3 perovskite solar cell

In ambient air, a long-chain dodecafluorosuberic acid (DFSA) with lower Young’s modulus was introduced to improve the mechanical compatibility of perovskite/carbon interface. Firstly, the carbonyl groups C O and F – in DFSA can passivate the intrinsic defects of perovskite, the DFSA effectively reduces the Young’s modulus of the perovskite and mitigates residual stress generated during perovskite annealing procedure. Most importantly, DFSA significantly enhances the Young’s modulus compatible degree between DFSA-CH 3 NH 3 PbI 3 (DFSA-MAPbI 3 , 35.8 GPa) and carbon (6.3 GPa), alleviating the interfacial stress concentration. Based on quantitatively analysis, interfical crack driving energy ( G d ) is reduced from 0.63 to 0.43 J m −2 , while the adhesive fracture energy ( G a ) is increased from 0.47 to 0.54 J m −2 , which reduces the probability of crack propagation and ductile delamination, and is conducive to the extraction and transmission of photogenerated carrior. This was also verified in finite element simulations. Finally, the photoelectric conversion efficiency (PCE) of the organic-inorganic hybrid perovskite (MAPbI 3 ) PSC device is improved from 10.27 % to optimal 14.12 %. After service at room temperature with relative humidity (RH) of 50–55 % and high temperature of 85 °C for 720 h, the original efficiency is maintained at 72 % and 89 %, respectively.