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Abstract Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a popular hole transport material in perovskite solar cells (PSCs). However, the devices with PEDOT:PSS exhibit large open‐circuit voltage (V_oc) loss and low efficiency, which is attributed to mismatched energy level alignment and the poor interface of PEDOT:PSS and perovskite. Here, three polymer analogues to polyaniline (PANI), PANI–carbazole (P1), PANI–phenoxazine (P2), and PANI–phenothiazine (P3) are designed with different energy levels to modify the interface between PEDOT:PSS and the perovskite layer and improve the device performance. The effects of the polymers on the device performance are demonstrated by evaluating the work function adjustment, perovskite growth control, and interface modification in MAPbI₃‐based PSCs. Low bandgap Sn–Pb‐based PSCs are also fabricated to confirm the effects of the polymers. Three effects are evaluated through the comparison study of PEDOT:PSS‐based organic solar cells and MAPbI₃ PSCs based on the PEDOT:PSS modified by P1, P2, and P3. The order of contribution for the three effects is work function adjustment > surface modification > perovskite growth control. MAPbI₃ PSCs modified with P2 exhibit a highV_ocof 1.13 V and a high‐power conversion efficiency of 21.06%. This work provides the fundamental understanding of the interface passivation effects for PEDOT:PSS‐based optoelectronic devices. 

This study explores conducting polymers with side chains containing long, branched alkyl groups as candidates for corrosion suppression coatings. These polymers, containing carbazole, phenothiazine, and phenoxazine cores, may be considered as analogues to polyaniline, which is often employed in corrosion control applications. The polymers are prepared from the corresponding dibrominated carbazole, phenothiazine, and phenoxazine monomers with 2,5-dimethyl-1,4-phenylenediamine by the Buchwald−Hartwig coupling reaction. The effectiveness of these coatings for corrosion suppression was tested by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The morphology of the coatings was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Corrosion testing of coated AISI 4130 steels in 3.5 wt % NaCl showed that the phenothiazine- and carbazole-containing polymers display excellent corrosion resistance. The protection efficiency (PE) of 95.9% for phenothiazine outperformed the other polymers, including polyaniline coating. SEM images indicate that the polymers are still uniformly coated with stable morphology after 24 h of exposure to corrosive media. These results suggest that phenothiazine and carbazole-based PANI analogues may be candidates for protective organic coatings in transportation, aviation, marine, and oil and gas industrial applications. 

Side chain alkyl groups have become the standard for incorporating solubilizing groups into conjugated polymers. However, the variety of alkyl groups available and their location on the polymer’s backbone can contribute to the packing of the polymer chains in many different ways, resulting in many different morphologies in the polymer that can affect its properties and performances. In this paper, we investigate the effects on the conductivity of nine phenothiazine-containing polyaniline derivatives (P1−P9) with alkyl or aryl side chains on the phenothiazine core while also varying the number of methyl groups on the p-phenylenediamine unit. 1H nuclear magnetic resonance spectroscopy, ultraviolet−visible spectroscopy, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, and wide-angle X-ray scattering (WAXS) were all used to study the polymers’ structures, physical and thermal properties, and morphologies. The t-butylphenyl substituent on the phenothiazine core seems to provide more rigidity in the polymer’s backbone resulting in higher Tg for series 3, while series 2 containing the 2-hexyldecyl-substituted polymers had the lowest Tg, which is attributed to the large volume of the side chain, that limits interchain interactions. Consequently, series 2 had the lowest conductivity. However, the strongest effect on the conductivity was seen from the tetramethyl groups on the PPDA unit, which resulted in the lowest conductivity in each series due to torsional strain (twisting) in the polymer’s backbone. The WAXS data suggest mostly amorphous films; thus, the conductivity in these materials seems to be dominated by a multiscale charge transport phenomenon that occurs in amorphous conjugated materials. Our results will aid in the understanding of side chain engineering of PANI derivatives for their optimum performances. 

Supercapacitor energy storage devices are well suited to meet the rigorous demands of future portable consumer electronics (PCEs) due to their high energy and power densities (i.e., longer battery-life and rapid charging, respectively) and superior operational lifetimes (10 times greater than lithium-ion batteries). To date, research efforts have been narrowly focused on improving the specific capacitance of these materials; however, emerging technologies are increasingly demanding competitive performance with regards to other criteria, including scalability of fabrication and electrochemical stability. In this regard, we developed a polyaniline (PANI) derivative that contains a carbazole unit copolymerized with 2,5-dimethyl-p-phenylenediamine (Cbz-PANI-1) and determined its optoelectronic properties, electrical conductivity, processability, and electrochemical stability. Importantly, the polymer exhibits good solubility in various solvents, which enables the use of scalable spray-coating and drop-casting methods to fabricate electrodes. Cbz-PANI-1 was used to fabricate electrodes for supercapacitor devices that exhibits a maximum areal capacitance of 64.8 mF cm–2 and specific capacitance of 319 F g–1 at a current density of 0.2 mA cm–2. Moreover, the electrode demonstrates excellent cyclic stability (≈ 83% of capacitance retention) over 1000 CV cycles. Additionally, we demonstrate the charge storage performance of Cbz-PANI-1 in a symmetrical supercapacitor device, which also exhibits excellent cyclic stability (≈ 91% of capacitance retention) over 1000 charge–discharge cycles.