Stability study in organic solar cells based on PTB7:PC71BM and the scaling effect of the active layer. (15th March 2018)

• Record Type: Journal Article
• Authors: Barreiro-Argüelles, Denisse; Ramos-Ortiz, Gabriel; Maldonado, José-Luis; Pérez-Gutiérrez, Enrique; Romero-Borja, Daniel; Meneses-Nava, Marco-Antonio; Nolasco, Jairo C.
• Is Part Of: Solar energy. Volume 163(2018)
• Page Start: 510
• Page End: 518
• Publication Date: 2018-03-15
• Subjects: PTB7:PCBM-based devices -- Scaling effect -- Stability -- Field's metal top electrode -- Lifetime -- Alternative electrodes -- ISOS protocols; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2018.01.090
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Highlights: Devices using PTB7:PC71 BM blend and an alternative top electrode are fabricated. Performance and stability is studied as a function of the active area. Environmental stability in presence of light, remains independent of active area. Environmental stability in absence of light is enhanced for scaled devices. Lifetime in our OPVs is determined mainly by intrinsic active layer instabilities. Abstract: Performance and stability of organic photovoltaic cells (OPVs) based on the benchmark bulk heterojunction PTB7:PC71 BM and the alloy Field's metal (FM) as top-electrode deposited by doctor blade technique, are fully studied when the active area is scaled by a factor of 25. Power conversion efficiency (PCE) of small active area (0.09 cm 2 ) devices resulted in 7.4 ± 0.8%, which is within the range of values commonly achieved for devices comprising Al as traditional, costly and nonstable top-electrode. However, PCE decreased 60% for scaled OPVs (2.25 cm 2 ). Studies of stability as a function of the active area were performed in accordance with the ISOS-L1 (laboratory simulation of constant lighting) and ISOS-D1 (shelf storage) protocols for devices tested in air and without encapsulation. The time to reach 50% of the initial PCE (T50 ) is about 14 h and 2000 h under ISOS-L1 and ISOS-D1 protocols, respectively, with a tendency of stability improvement for scaled devices. A whole PV analysis through the single diode model, impedance spectroscopy, and light beam induced voltage (LBIV) measurements is presented. Our results are a good indication that FM top-electrode, of cheap and easy deposition under vacuum free conditions, provides an acceptable photovoltaic performance after scaling the active area.