Low-Cost Upscaling Compatibility of Five Different ITO-Free Architectures for Polymer Solar Cells

Five different indium-tin-oxide free (ITO-free) polymer solar cell architectures provided by four participating research institutions that all presented a laboratory cell performance sufficient for use in mobile and information and communication technology (ICT) were evaluated based on photovoltaic performance and lifetime tests according to the ISOS protocols. The comparison of the different device architectures was performed using the same active material (P3HT: PCBM) and tested against an ITO-based reference device. The active area was 1 cm2 and rigid glass or flexible polyester substrates were employed. The performance results were corroborated by use of a round robin methodology between the four participating laboratories (DTU/DK, ECN/NL, Frauenhofer ISE/DE, and the Holst Centre/NL), while the lifetime testing experiments were carried out in only one location (DTU). Five different lifetime testing experiments were carried out for a minimum of 1000 h: (1) shelf life (according to ISOS-D-1); (2–3) stability under continuous 1 sun illumination (1000 Wm_2, AM1.5G) at low (37 6 3_C) and high (80 6 5_C) temperatures (according to ISOS-L-1 and ISOS-L-2); (4) stability under continuous low-light conditions at 0.1 sun (100 Wm_2, AM1.5G, 32_C) (according to ISOS-LL); (5) continuous illumination (670 Wm_2, AM1.5G) at high temperature (65_C) and high humidity (50% RH) (according to ISOS-L-3). Finally, the upscaling compatibility of these device architectures based on the device photovoltaic behavior, stability and scalability were identified and we confirm that an architecture that presents a high score in only one aspect of the solar cell performance is not sufficient to justify an investment in upscaling. Many will require further technical development. © 2013 Wiley Periodicals, Inc.