Non-fullerene organic solar cells with 7% efficiency and excellent air stability through morphological and interfacial engineering

Abstract

We report on the fabrication of the 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) and poly{[N,N-9-bis(2-octyldodecyl)- naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)}(P(NDI2OD-T2)) active layer combination employing air brush spray coating technique in 2-methyl anisole. Optical absorption characteristics of the blend layer were examined utilizing UV–visible spectra in the wavelength sweep varying from 300 to 900 nm. Atomic force microscopy was utilized to analyze the surface characteristics of the fabricated active layer. Under the radiance of simulated solar light with 100 mW cm−2 (AM 1.5G), the current density voltage (J-V) characteristics were determined by employing a solar simulator. Fullerene-free organic solar cells were build using a combination of P(NDI2OD-T2) acceptor and a polymer donor PTB7 with SnO2 acting as an interlayer, which showed power conversion efficiency (PCEs) of more than 7.0%, which is considered as the best PCEs been reported for the chosen donor and the acceptor. The device is extremely stable, holding 75% of its unique effectiveness subsequent to being put away in air for 72 days even without encapsulation. These outcomes demonstrate that the spray-coated film is a feasible contrasting option to the vacuum-deposited ITO film in terms of cost for mass production and for roll-to-roll based organic solar cells.