Development of moisture-proof polydimethylsiloxane/aluminum oxide film and stability improvement of perovskite solar cells using the film

A method for enhancing the moisture barrier property of polydimethylsiloxane (PDMS) polymer films is proposed. This is achieved by filling the PDMS free volume with aluminum oxide (AlO(x)). To deposit AlO(x) inside PDMS, thermal atomic layer deposition (ALD) is employed. The PDMS/AlO(x) film thus produced has a 30 nm AlO(x) layer on the surface. Its water vapor transmission rate (WVTR) is 5.1 × 10(−3) g m(−2) d(−1) at 45 °C and 65% relative humidity (RH). The activation energy of permeability with the PDMS/AlO(x) film for moisture permeation is determined to be 35.5 kJ mol(−1). To investigate the moisture barrier capability of the PDMS/AlO(x) layer, (FAPbI(3))(0.85)(MAPbBr(3))(0.15)/spiro-OMeTAD/Au perovskite solar cells are fabricated, and encapsulated by the PDMS/AlO(x) film. To minimize the thermal damage to solar cells during ALD, AlO(x) deposition is performed at 95 °C. The solar cells exposed to 45 °C-65% RH for 300 h demonstrate less than a 5% drop in the power-conversion efficiency.