Understanding\nProcess–Structure Relationships\nduring Lamination of Halide Perovskite Interfaces

Fabrication\nof halide perovskite (HP) solar cells typically involves\nthe sequential deposition of multiple layers to create a device stack,\nwhich is limited by the thermal and chemical incompatibility of top\ncontact layers with the underlying HP semiconductor. One emerging\nstrategy to overcome these restrictions on material selection and\nprocessing conditions is lamination, where two half-stacks are independently\nprocessed and then diffusion bonded to complete the device. Lamination\nreduces the processing constraints on the top side of the solar cell\nto allow new device designs, expanded use of deposition methods, and\nself-encapsulation of devices. While laminated perovskite solar cells\nwith high efficiencies and novel interlayer combinations have been\ndemonstrated, there is a limited understanding of how the lamination\nprocess parameters affect the diffusion-bond quality and material\nproperties of the resulting HP layer. In this study, we systematically\nvary temperature, pressure, and time during lamination and quantify\nthe resulting impacts on bonded area, grain domain size, and photoluminescence.\nA design of experiments is performed, and statistical analysis of\nthe experimental results is used to quantitatively evaluate the resulting\nprocess–structure–property relationships. The lamination\ntemperature is found to be the key parameter controlling these properties.\nA temperature of 150 °C enables successful bonding over 95% of\nthe substrate area and also results in increases in apparent grain\ndomain size and photoluminescence intensity. Based on these insights,\nthe lamination temperature of functional perovskite solar cell devices\nis varied, demonstrating the importance of the resulting bond quality\non device performance metrics.