Substrate modifications for stability improvements of flexible perovskite solar cells

Abstract

Flexible perovskite solar cells (fPSCs) prepared on flexible plastic substrates exhibit poor stability under illumination in ambient, due to inferior gas barrier properties of plastic substrates. Herein, we investigated effect of different modifications of the back surface of the substrate to improve stability under illumination in ambient. T80 under simulated solar illumination at maximum power point in ambient (ISOS-L-1) can be increased from 80 h to over 350 h with the deposition of a single layer (by spin-coating or by atomic layer deposition (ALD)). While ALD layers resulted in the best T80 value and significant reduction of the oxygen transmission rate compared to other modifications even for very low film thickness (≈10 nm), a simple solution-processed spin-on-glass barrier layer also enables significant (more than 4 times) improvement in device stability. This work illustrates the importance of barrier layers for decreasing the ingress of oxygen and moisture into fPSCs through the plastic substrate.