Comparative study of PTB7:PC71BM based polymer solar cells fabricated under different working environments

In this article, we have evaluated the performance of inverted organic solar cells (OSCs) fabricated under ambient air and inert environment. Here, poly([4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b ']dithiophene-2,6-diyl]{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) donor with [6,6]-phenyl C70-butyric acid methyl ester (PC71BM) acceptor were employed as a photoactive layer. The calculated power conversion efficiency (PCE) from current-voltage (J-V) characteristics for a device fabricated under an inert environment is 6.90% as compared to 3.96% for a device fabricated in ambient condition (25 degrees C, 100 kPa). The results revealed that the device processed in ambient conditions degrades the photovoltaic performance parameters, and the PCE decreased by 42.62% as compared to the devices fabricated in an inert environment. Along with this, we have also discussed in detail, the effect of the working environment on photoactive layers by Raman spectroscopy. The UV-Vis spectroscopy and Atomic Force Microscopy (AFM) techniques are presented to illustrate the optical properties and morphology of the photo-active layer respectively.