High Performance Roll-to-Roll Produced Fullerene-Free Organic Photovoltaic Devices via Temperature-Controlled Slot Die Coating

Solution-processed organic photovoltaics (OPVs) have continued to show their potential as a low-cost power generation technology; however, there has been a significant gap between device efficiencies fabricated with lab-scale techniques—i.e., spin coating—and scalable deposition methods. Herein, temperature-controlled slot die deposition is developed for the photoactive layer of OPVs. The influence of solution and substrate temperatures on photoactive films and their effects on power conversion efficiency (PCE) in slot die coated OPVs using a 3D printer-based slot die coater are studied on the basis of device performance, molecular structure, film morphology, and carrier transport behavior. These studies clearly demonstrate that both substrate and solution temperatures during slot die coating can influence device performance, and the combination of hot substrate (120 °C) and hot solution (90 °C) conditions result in mechanically robust films with PCE values up to 10.0% using this scalable deposition method in air. The efficiency is close to that of state-of-the-art devices fabricated by spin coating. The deposition condition is translated to roll-to-roll processing without further modification and results in flexible OPVs with PCE values above 7%. The results underscore the promising potential of temperature-controlled slot die coating for roll-to-roll manufacturing of high performance OPVs.