| 초록 |
The mechanical robustness of polymer solar cells (PSCs) is of great importance to ensure the long-term stability and enable their use as power-generators in flexible and stretchable electronics. Here, we present a comparative study of the mechanical properties of small-molecule acceptor (SMA)-based, polymer acceptors (PA)-based, and fullerene-based PSCs. To understand the difference between the mechanical properties of SMA-based and PA-based PSCs, we control the number-average molecular weight (Mn) of P(NDI2OD-T2) from 15 to 163 kg mol-1 in all-PSCs. The high Mn PA-based-PSCs exhibited a high strain at fracture of 31.1%, which is 9- and 28-fold higher than those of SMA-PSCs and PCBM-PSCs, respectively. The superior mechanical robustness of all-PSCs is attributed to using a PA above the critical molecular weight (Mc), which produces tie molecules and polymer entanglements that dissipate substantial mechanical strain energy with large plastic deformation. |
