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

Abstract

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, (FAPbI₃)_0.85(MAPbBr₃)_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.