A nonvolatile “resistive random access memory” (ReRAM) device is reported with a series of four conjugated polymers (CPs) containing poly­[2,7-(9,9′-dioctyl­fluorene)-co-N-phenyl-1,8-naphthalimide (PFO–NPN) as donor and acceptor, respectively. A single layer, thin film of PFO–NPN copolymer that is sandwiched between indium tin oxide (ITO) and aluminum shows bistable property with a remarkably high I on/I off ratio of 108. The charge transport of the polymer is studied by fitting I–V curves with various conduction models to realize that the trap charge limited current (TCLC) assists in switching and exhibiting bistable property of the memory device. Theoretical calculations were also performed on the polymer to elucidate the presence of traps on the carbonyl oxygen atoms of NPN moiety. In addition, ReRAM properties like I on/I off ratio and write voltage were also tuned by changing the concentration of the acceptor moiety. Four different copolymers of acceptor concentrations (5%, 10%, 35%, and 50%) with respect to donor concentrations were characterized as a memory device. The device with high acceptor concentration (50%) showed the lowest I on/I off ratio (103) and write voltage (0.8 V). It was also observed experimentally that the I on/I off ratio and write voltage decrease sequentially with an increase in the acceptor concentration, thereby providing flexibility in tuning the memory parameters by allowing a molecular level change in the active material. The optical studies were performed to elucidate the mechanism of the tunable memory characteristic of the polymer, and the results reveal that the tunability is achieved due to the variation in the injection barrier and the strength of ICT for the different polymers.

Hybrid perovskite solar cells (PVSCs) are extremely susceptible to moisture and heat which restricts their commercial viability. Herein, three multifunctional fluoroaromatic amine additives i.e. 4-fluoroaniline (FA), 2,4,6-trifluoroaniline (TFA) and 2,3,4,5,6-pentafluoroaniline...

The effects of the electron injection barrier on the charge transport, brightness and the electroluminescence (EL) properties of polymer light emitting diodes (PLEDs) with poly(9-vinylcarbazole) (PVK) as an emissive layer have been studied. By using Al and LiF/Al as the cathode in single layer PLEDs and diverse electron transporting layers (ETLs) such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen) and 2,2',2''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) in the case of multilayer PLEDs, the charge transport, brightness, color tuning and the EL properties of the devices were drastically modified. The energy barrier for electrons affects the electron current flowing through the device, thereby affecting the operating voltage and the brightness of the PLEDs. The PLEDs with TPBi as the ETL possess the lowest injection barrier and give the maximum brightness of 426.24 cd m. The electron injection barrier is also found to play a major role in defining the EL spectra of the PLEDs. A larger injection barrier gives rise to electroplex formation in the EML-ETL interface of the PLEDs and an additional peak at ∼605 nm was observed in the EL spectrum. As a result, a near white emission with CIE coordinates of (0.30, 0.30) and (0.25, 0.23) at 20 V was obtained from devices with BCP and BPhen as ETLs. Furthermore, PVK doped with 2-phenyl-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) at 10, 20 and 30 wt% ratios modified the electron transport nature of PVK and had a remarkable influence on the aforesaid properties, especially on the electroplex formation.

In recent times the perovskite solar cells (PVSCs) have emerged as the most preeminent candidates among renewable technologies, yet the instability of PVSCs in ambient condition has hindered its progress...