Transparent and Conductive Inorganic/Polymer‐Composite Encapsulants for Long‐Term Perovskite Solar Cells Operation

An innovative inorganic/polymer‐composite encapsulation scheme comprising a polymer‐based transparent conductive composite (TCC) coupled with a transparent conductive oxide is introduced to extend the lifetime of moisture‐sensitive devices such as perovskite solar cells (PSC). The TCC comprises conductive silver‐coated polymethyl methacrylate (Ag‐PMMA) microsphere fillers protruding from a transparent non‐conductive polymer matrix. TCC samples (5% Ag‐PMMA by area) demonstrate high optical transparencies (%T approx. 85% in the 370–1200 nm region), low out‐of‐plane electrical resistivities (R < 0.2 Ω cm 2 ), and equilibrium permeabilities of less than 1 g mm/m 2 /day, all of which are well‐maintained after 1,000 hours of environmental exposure. In practice, the TCC is employed between two indium zinc oxide (IZO) thin films, with the in‐plane conductivity of IZO and the out‐of‐plane conductivity of TCC working collectively to function as a single encapsulating electrode. This encapsulation scheme is exemplified by benchmarking performances of PSCs subjected to accelerated aging conditions of quasi‐maximum power point tracking under light soaking in air at 50 °C, 40% R.H. to 60% R.H. Notable improvements in operational lifetimes are observed, with a champion encapsulated PSC maintaining over 90% of its initial efficiency of 21.65% for up to 1,430 hours, compare to less than 300 hours for an unencapsulated control.