Zicheng Ding,* Yi Zhang, Yueling Su, Yin Wu, Yanchun Han, 

Kui Zhao,* and Shengzhong (Frank)

Liu *

ABSTRACT:

Stretchable organic solar cells (OSCs) have great potential as power sources for the nextgeneration wearable electronics. Although blending rigid photovoltaic components with soft
insulating materials can easily endow the mechanical ductility of active layers, the photovoltaic
efficiencies usually drops in the resulting OSCs. Herein, a high photovoltaic efficiency of 15.03%
and a large crack-onset strain of 15.70% is simultaneously achieved based on a ternary blend
consisting of polymer donor poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-
b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-
c′]dithiophene-4,8-dione)] (PM6), non-fullerene accepter 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-
3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-
e]thieno[2″,3′′:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-
diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-
diylidene))dimalononitrile (Y6), and soft elastomer polystyrene-block-poly(ethylene-ranbutylene)-block-polystyrene (SEBS) through the control of phase separation and crystallization.
By employing a high boiling-point solvent additive 1-chloronaphthalene (CN) with different
solubilities for PM6 and Y6, the aggregation dynamics of PM6 and Y6 as well as the film
solidification process are dramatically altered, allowing for the different molecular rearrangement
and liquid–liquid phase separation evolution. Consequently, the ternary film with optimal CN
content presents decreased SEBS domains and moderately improved molecular ordering of PM6
and Y6, enabling effective mechanical deformation and charge generation/transport. The revealed
corrections between the film formation process, film microstructure and photovoltaic/mechanical
characteristics in the ternary blend provide deep understanding of the morphology control towards
high-performance stretchable OSCs.

doi:
10.1002/eem2.12421