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Abstract Interfacial compatibility between the electrode and organic semiconductor plays a critical role in controlling the charge transport and hence efficiency of organic solar cell. Here, we introduce a novel small-molecule zwitterionic electrolyte (S1) combined with ZnO as electron transporting interlayer employed for the inverted PTB7:PC 71 BM bulk heterojunction solar cell. The resulting device with the S1/ZnO stacked interlayer achieves a high PCE of 8.59%, obtaining a 16.2% improvement over the control device performance of 7.4% without the S1 attributed to the significant increased short-circuit current density and fill factor. The interfacial properties are investigated. It is found that the S1/ZnO interlayer possess an ultralow work function of 3.6 eV, which originates from the interfacial double dipole step induced by the zwitterionic side chain electrostatic realignment at interface. The S1/ZnO interlayer exhibits the excellent charge extraction ability, suppresses the charge recombination loss and decreases the series resistance at the active layer/electrode contact. Graphical abstract Image 1 Highlights • S1 coated ZnO layer is employed as electron transporting layer for inverted organic solar cell. • S1/ZnO stacked interlayer exhibits the excellent charge extraction ability. • ZnO/S1 stacked interlayer has an ultralow work function of 3.6 eV. • The efficiency of the device with the S1/ZnO interlayer constitutes a 16.2% improvement over that of the controlled device. [ABSTRACT FROM AUTHOR]

Persistent photoconductivity (PPC) behavior in organic phototransistors has fascinating potentials in applications of photoelectronic devices. A key issue is how the presence of air affects the PPC behavior. Here, combining with the theoretical and experimental results, the PPC behavior is associated with photogenerated electrons trapped in oxygen atom-induced the reduced Lowest Unoccupied Molecular Orbitals or oxygen molecule-induced new trap state within energy bandgap of organic semiconductor. Inspired by the potential applications arising from the PPC behavior, organic memory phototransistors (OMPTs) are achieved by light programming and electrical erasing. The OMPTs show bistable current states as well as long retention times. Our results suggested that oxygen in air plays a key role in PPC behavior and provides a guidance for controlling the PPC behavior toward integrated multifunctional optoelectronic devices. [Display omitted] • 2DMCs are used as OSCs layer to rule out the influence of grain boundaries on OPTs. • PPC behavior can be obtained when OPTs measured in air compared with OPTs measured under vacuum. • Oxygen-induced trap states play a critical role in PPC behavior. • Memory characteristics arising from PPC behavior are investigated. [ABSTRACT FROM AUTHOR]