Materials, methods and strategies for encapsulation of perovskite solar cells: From past to present

In the past decade perovskite solar cells have received immense attention and an astounding advance in terms of power conversion efficiency is achieved. The best achieved power conversion efficiency for single junction device is around 25 % which is comparable to the well-established and commercialized silicon solar cell technology. The poor lifetime and stability of these devices remain a major bottleneck, which needs to be resolved quickly as these factors play a significant hurdle towards commercialization of this technology. Apart from developing new stable perovskite material and optimizing the device architecture, a robust barrier/encapsulation with high barrier performance materials is one of the best ways to address the poor lifetime/stability problems encountered in these devices. Polymer based encapsulation methodology can satisfy both the needs of maintaining a balance between processing cost and device lifetime. In this review article an extensive outline on the degradation mechanisms commonly seen in perovskite solar cells is first accounted. In depth analysis about the various requirements an encapsulant material must satisfy and different types of encapsulant materials that were used earlier as an encapsulant in perovskite solar cells are explained. Various techniques that are commonly adopted for the encapsulation procedure is discussed briefly. This review is concluded by mentioning few promising strategies in encapsulation which could help in improving the overall device stability and lifetime of perovskite solar cells.