Organic photovoltaics (OPVs) have unique advantages of
low weight,
mechanical flexibility, and solution processability, which make them
exceptionally suitable for integrating low-power Internet of Things
devices. However, achieving improved operational stability together
with solution processes that are applicable to large-scale fabrication
remains challenging. Their major limitation arises due to the instable
factors that occur both inside the thick active film and from the
ambient environment, which cannot be completely resolved via the current
encapsulation techniques used for flexible OPVs. Additionally, thin
active layers are highly vulnerable to point defects, which result
in low yield rates and impede the laboratory-to-industry translation.
In this study, flexible fully solution-processed OPVs with improved
indoor efficiency and long-term operational stability than that of
conventional OPVs with evaporated electrodes are achieved. Benefiting
from the oxygen and water vapor permeation barrier of the spontaneously
formed gallium oxide layers on the exposed eutectic gallium–indium
surface, fast degradation of the OPVs with thick active layers is
prevented, maintaining 93% of its initial P
max after 5000 min of indoor operation under 1000 lx light-emitting
diode (LED) illumination. Additionally, by using the thick active
layer, spin-coated silver nanowires could be directly used as bottom
electrodes without complicated flattening processes, thereby substantially
simplifying the fabrication process and proposing a promising manufacturing
technique for devices with high-throughput energy demands.