BRIEF PAPER: QUANTIFYING SPATIAL HETEROGENEITY OF LAMINATED PEROVSKITE SEMICONDUCTORS USING PHOTOLUMINESCENCE MAPPING

Halide perovskite solar cells (PSCs) are a state-of-the-art photovoltaic technology that exhibit high efficiencies and can be manufactured using roll-to-roll systems. However, PSCs are currently fabricated using sequential layer-by-layer deposition, which constrains the selection of suitable functional layers in the solar cell and limits the processing conditions and techniques that can be used. Lamination via diffusion bonding is a scalable parallel-processing technique that has the capability to overcome some of the challenges of sequential deposition by widening the thermal processing window and reducing the chemical compatibility requirements for PSC manufacturing. However, there remains a lack of detailed understanding of the process-structure-property relationships needed to accelerate the development of high-volume lamination-based manufacturing processes. In this work, we introduce a method to study the process-structure-property relationships of laminated perovskite semiconductors by using a custom photoluminescence (PL) spectroscopy system to quantify spatial heterogeneity in laminated halide perovskite (HP) materials. PL is an important figure-of-merit used to quantify the optoelectronic properties of semiconductor materials used in PV manufacturing. The spatial variation in PL of a laminated HP film is compared to that of an unlaminated HP film. The PL system uses servomotors and an Arduino microcontroller to automate a PL mapping procedure. The PL equipment is tunable to achieve a minimum possible spot size of similar to 50 mu m, enabling high-resolution measurements. The system is used to measure the PL of 19 separate locations on both a laminated and unlaminated HP material. The results of this study reveal that lamination at optimal conditions will improve the average PL peak intensity of the HP by 55%, indicating that lamination has the potential to improve the optoelectronic characteristics of PSCs. However, lamination also increases the standard deviation of PL peak intensity. Therefore, although lamination improves the PL of HPs, it also induces unwanted spatial heterogeneity. This warrants future studies on the governing physical mechanisms that determine quality control metrics in lamination-based PSC manufacturing.