(Invited) Critical Parameters for GW Scale Perovskite PV Manufacturing

Abstract

A recent NREL white paper proposing a new US Perovskite Energy Consortium states “Fulfilling the world’s demand for PV requires continued exponential growth of production capacity without exponential growth in capital expenditure and remains a major challenge due to the inadequate capital efficiency of PV using existing technologies. There is an opportunity and a need for disruptive and fundamentally profitable technologies to supplement the ongoing growth of the PV manufacturing industry”. Perovskite technology promises high conversion efficiency, low manufacturing cost, and low capital expense (CapEx) to build manufacturing capacity. Fulfilling that promise requires a manufacturing process with a very high throughput. The ability to fabricate perovskite films using low-temperature, solution based methods has been touted as a path to low cost and low CapEx manufacturing, however fast deposition of the perovskite layer alone is not sufficient to create the throughput that transforms the PV manufacturing landscape; an in-line process that integrates the deposition of all the functional layers of the device, as well as cell interconnects and module lamination, is required. Any slow vacuum deposition step (e.g., sputtering ITO for the transparent conductor) or long thermal annealing step (e.g., forming a charge transport barrier by forming a compact TiO2 layer) commonly used in lab-scale perovskite device fabrication must be avoided. Our cost modeling shows that the throughput of a single line needed to get to disruptive CapEx and manufacturing cost will be on the order of 45 m2/min. That results in over 3GW/year production capacity at conservative uptime and yield values. An integrated in-line roll-to-roll (RtR) process with a 1.5m wide web would require all deposition steps to run at 30 m/min; much faster than processes cited in the academic literature for lab scale devices. That line speed is not taxing to most commercially available RtR systems, but practical limitations on oven size means a tight window for drying and annealing steps of all solution coated layers. The challenges of creating high performance transparent conductors, inorganic charge transport and barrier layers, perovskite layers and cell interconnects at those speeds will be discussed. The implied TAKT time is less than 3 seconds for 2m2 modules coming off of a single production line. The final assembly and test operations take much longer for each module, so methods of dealing with the mismatch must be implemented. We will also describe the practical considerations, including material sourcing and process requirements for production at GW scale.