Ambient Air-Stable CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf>Perovskite Solar Cells Using Dibutylethanolamine as a Morphology Controller

Abstract

Hybrid inorganic-organic perovskite solar cells have gained increased attention due to their easy processing and exceptional power conversion efficiencies. However, their limited stability against moisture, light, and heat remains an issue. Various solution-processing techniques, particularly, additive engineering or additive-enhanced deposition, have been used to tune the morphology of the perovskite films in order to achieve stable and high-quality films. Herein, we report the successful use of dibutylethanolamine (DBEA) as a multifunctional morphology-controlling additive to deposit high-quality homogeneous films with grain sizes as large as ∼5 μm under ambient processing conditions (∼50% RH). DBEA, due to its ability to donate lone pairs and to make hydrogen bonds with the inorganic octahedra of perovskite crystals, was used to achieve a stable and uniform absorbing layer with high efficiency compared to that of pristine or dimethyl sulfoxide (DMSO)-based perovskites. The high boiling point of this additive also helped in achieving high efficiency by slowing down the crystallization process and increasing the crystal size to the micron range. The best performing device with DBEA showed the highest efficiency of 11.51%, while devices prepared from DMSO (DMSO:DMF 30:70 V/V) and without any additive (DMF only) were only 6.78 and 4.51% efficient, respectively. A similar trend was also observed for the ambient air stability of these materials with both DBEA and additive-free devices completely degrading within 350 h, while DBEA-incorporated devices retained ∼80% of their initial efficiency even after 525 h of ambient air storage.