The ternary blending strategy of introducing a third component into the binary organic solar cells (BOSCs) is a feasible and efficient strategy to optimize the performance of BOSCs. Ternary organic...
The electron transport layer (ETL)
exerts a dramatic influence
on the power conversion efficiency (PCE) of the nonfullerene organic
solar cells (NOSCs). Currently, the majority of the organic ETLs possess
a relatively poor conductivity, which is not conducive to carrier
transport and collection. Herein, we design and develop a novel hyperbranched
conjugated polyelectrolyte (CPE) based on n-type perylene diimide
(PDI) as the center core and quaternary ammonium salt as the side
polar groups. The lone pair electrons of the nitrogen atoms can transfer
to the electron deficient PDI core and endow the molecule with an
efficient n-type self-doping effect. Moreover, the hyperbranched structure
makes the molecule functionalized with more side polar groups, favoring
forming more dipoles and stronger dipole moments. Therefore, the CPE
PTPAPDINO possesses a high conductivity and can notably decrease the
work function (WF) of the electrode, contributing to the carrier transport
and collection of the device. The NOSC with PTPAPDINO as ETL delivers
an excellent PCE of 15.62%, which is even superior to the device using
the classical PDINO ETL. Moreover, the PCE can retain 82.6% of the
optimal device when the thickness has been increased to 28 nm. These
results manifest that it is a feasible strategy to design an n-type
self-doping hyperbranched CPE as efficient ETL, and PTPAPDINO is a
promising alternative ETL for high performance NOSCs.
It is incredibly feasible and effective to adopt a solid additive strategy to optimize the active layer blend films morphology for nonfullerene organic solar cells (OSCs) to achieve high efficiency and stable performance. Herein, a novel amorphous small molecule SJ‐IC‐M with a comparatively high molecular weight is first designed and used as an efficient solid additive in the OSCs based on PM6:Y6 to enhance the power conversion efficiency (PCE) and long‐term stability of the device. After the addition of 0.5 wt% SJ‐IC‐M into the active layer blends, the PCE can be increased to 16.2% compared with that of the reference device without additive displaying an inferior PCE of 15.0%. Moreover, the device containing the SJ‐IC‐M additive delivers more excellent long‐term stability. The PCE can remain over 90% of its initial value when the unencapsulated device is preserved in a N2‐filled glovebox for a month. Systematic analysis reveals that the introduction of the relatively high molecular weight amorphous SJ‐IC‐M additive can optimize the crystallinity of Y6. As a result, an improved charge transport, stabilized blend morphology, and enhanced device performance are achieved. Moreover, the current research provides a new strategy which can replace the commonly used solvent additive to fabricate efficient and stable nonfullerene OSCs.
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