S. Masi, A. Rizzo, R. Munir, A. Listorti, A. Giuri, C. Esposito Corcione, N.D. Treat, G. Gigli, A. Amassian, N. Stingelin, S. Colella
Advanced Energy Materials, (2017)
Low-molecular-weight organic gelators are widely used to influence the
solidification of polymers, with applications ranging from packaging
items, food containers to organic electronic devices, including organic
photovoltaics. Here, this concept is extended to hybrid halide
perovskite-based materials. In situ time-resolved grazing incidence
wide-angle X-ray scattering measurements performed during spin coating
reveal that organic gelators beneficially influence the nucleation and
growth of the perovskite precursor phase. This can be exploited for the
fabrication of planar n-i-p heterojunction devices with MAPbI3 (MA = CH3NH3+) that display a performance that not only is enhanced by ≈25%
compared to solar cells where the active layer is produced without the
use of a gelator but that also features a higher stability to moisture
and a reduced hysteresis. Most importantly, the presented approach is
straightforward and simple, and it provides a general method to render
the film formation of hybrid perovskites more reliable and robust,
analogous to the control that is afforded by these additives in the
processing of commodity “plastics.”