Novel laser-assisted glass frit encapsulation for long-lifetime perovskite solar cells

Abstract

Hermetic encapsulation protects perovskite solar cells (PSCs) from degradations induced by humidity and oxygen. A novel dual laser beam glass frit sealing process is developed and optimized to hermetically encapsulate PSCs. A 3D transient phenomenological model of the laser-assisted encapsulation is developed, validated and used to optimize the glass sealing procedure. During the laser-sealing process, the cells are subjected to 65 +/- 5 degrees C for a short time of <60 s. This extremely low process temperature glass sealing procedure is applied to encapsulate n-i-p PSCs fabricated with a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) hole transport layer (HTL). The long-term stability of the encapsulated PSCs is examined under elevated humidity conditions and by thermal cycling tests. No performance variations after 500 h of humidity aging at 85% RH and 50 thermal cycles of -40 degrees C to 65 degrees C are observed. Though a 16% PCE loss is observed after thermal cycles between -40 degrees C and 85 degrees C, XRD analysis revealed no perovskite decomposition and the performance losses are assigned to the thermal degradation of the HTL material. A hermetic encapsulation is a critical step for the transition of PSCs from the laboratory to the market and this glass encapsulation ensures a successful path towards the commercialization of these emerging PV devices.