Revealing the Chemistry and Morphology of Buried Donor/Acceptor Interfaces in Organic Photovoltaics.

With power conversion efficiencies (PCEs) of <13% and plagued by stability issues, organic photovoltaics (OPVs) still lack wide adoption, despite significant recent advances. Currently, the most progress in OPV device performance is achieved by "trial-and-error" preparation procedures that lead to complex and largely unknown-despite tremendous analytical efforts-morphologies. Here, we demonstrate a proof-of-principle, chemical imaging methodology that combines experimental high spatial sensitivity and chemical selectivity with theoretical modeling, capable of analyzing the three-dimensional composition and morphology of virtually any device.

Reversible and Irreversible Electric Field Induced Morphological and Interfacial Transformations of Hybrid Lead Iodide Perovskites.

We report reversible and irreversible strain effects and interfacial atomic mixing in MAPbI/ITO under influence of external electric bias and photoillumination. Using conductive-probe atomic force microscopy, we locally applied a bias voltage between the MAPbI/ITO and the conductive tip and observed local dynamic strain effects and current under conditions of forward bias. We found that the reversible part of the strain is associated with a current spike at the current onset stage and can therefore be related to an electrochemical process accompanied by local molar volume change.