Conversion efficiency enhancement of methylammonium lead triiodide perovskite solar cells converted from thermally deposited lead iodide via thin methylammonium iodide interlayer

Abstract The thermally deposited thin methylammonium iodide (MAI) interlayer worked as protection layer of poly (3, 4-ethylenedioxythiophene) poly (styrene sulfonate) (PEDOT:PSS) in the thermal deposition of lead iodide (PbI2). And the thin MAI interlayer could be the MAI supplemental layer during converting the thermally deposited PbI2 into perovskite. The performances of perovskite solar cells (SCs) converted from thermally deposited PbI2 were remarkably enhanced by using the thin MAI interlayer on PEDOT:PSS. The short-circuit current density (JSC), fill factor (FF%), and conversion efficiency (η%) of perovskite SCs converted from thermally deposited PbI2 increased with the initial increase in thickness of the thin MAI interlayer and then reduced when the thickness of thin MAI interlayer exceeded 2.2 nm. Perovskite SCs converted from thermally deposited PbI2 with a 2.2 nm-thick thin MAI interlayer obtained the largest JSC, FF%, and η% at 19.44 mA/cm2, 74% and 12.75%, respectively, in our study. And the largest JSC was more than twice larger than that of perovskite SCs converted from thermally deposited PbI2 without thin MAI interlayer. Although the perovskite SCs converted from thermally deposited PbI2 without thin MAI interlayer has η% much less than that of perovskite SCs converted from spin-coated PbI2. The perovskite SCs converted from thermally deposited PbI2 with 2.2 nm-thick thin MAI interlayer had an η% of 12.75%, which was larger than that of perovskite SCs converted from spin-coated PbI2 at 10.57%.