화학공학소재연구정보센터
Solar Energy, Vol.163, 510-518, 2018
Stability study in organic solar cells based on PTB7:PC71BM and the scaling effect of the active layer
Performance and stability of organic photovoltaic cells (OPVs) based on the benchmark bulk heterojunction PTB7:PC71BM 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 (T-50) 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.