Soft Polymer–Organolead Halide Perovskite Films for Highly Stretchable and Durable Photodetectors with Pt–Au Nanochain-Based Electrodes

The rigid and brittle nature of methylammonium lead iodide (MAPbI 3 ) polycrystalline films limits their application in stretchable devices due to rapid deterioration in performance on cycling. By incorporation of polymer chains in the MAPbI 3 films, a strategy to alter the mechanical modulus and the viscoelastic nature of the films has been developed. Combining this with flexible nanochain electrodes, highly stretchable and stable perovskite devices have been fabricated. The resultant polymer-MAPbI 3 photodetector exhibits ultralow dark currents (∼10 –11 A) and high light switching ratios (∼10 3 ) and maintains 75% of performance after 30 days. The viscoelastic nature and lower modulus of the polymer improve the energy dissipation in the polymer-MAPbI 3 devices; as a result, they maintain 52% of the device performance after 10000 stretching cycles at 50% strain. The difference in the mechanical behavior is clearly observed in the failure mode of the two films. While rapid catastrophic cracking is observed in MAPbI 3 films, the intensity and size of such crack formation are highly limited in polymer-MAPbI 3 films, which prevent their failure.