Polymer-induced lattice expansion leads to all-inorganic CsPbBr3 perovskite solar cells with reduced trap density

All-inorganic perovskite materials (CsPbBr3) with long-term stability have been attracted enormous attention for commercialization. Here, a one-step spin-coating method was employed to yield high-purity CsPbBr3 perovskite films. The polyethylene glycol (PEG) was introduced into a precursor solution to balance the nucleation and growth rate. Noticeably, adding a polymeric material of PEG also leaded to a uniform lattice expansion in CsPbBr3 thin layers. The polymer-induced lattice expansion benefits the performances of a CsPbBr3 device due to reduced trap density, boosting the power conversion efficiency. This work emphasizes that controlled lattice expansion benefits in enhancing the electronic functionalities of perovskites.