Towards efficient perovskite light-emitting diodes: A multi-step spin-coating method for a dense and uniform perovskite film

Although organometal halide perovskites are emerging as emitters with extremely high color purity and low cost, device performances are significantly restricted by poor morphology of the perovskite layer. In this work, a multi-step spin-coating method is used to prepare CH₃NH₃PbBr₃ perovskite layer, which a dense and uniform perovskite film with small grain sizes and a ∼100% coverage. Moreover, the component of the hole injection layer poly(3,4-ethylenedioxythio- phene):poly(4-styrenesulphonate) (PEDOT:PSS) adjusted with PSS is applied to reduce the injection barrier between PEDOT:PSS and perovskite layer. With above-mentioned approaches, efficient perovskite light-emitting diodes with maximum luminance and current efficiency of 9900 cd m⁻² and 2.6 cd A⁻¹ are eventually acquired.