Recently, carbazole‐based self‐assembled monolayers (SAMs) have been utilized as hole transport layers (HTLs) in perovskite solar cells. However, their application in Sn or mixed Sn/Pb perovskite solar cells has been hindered by the poor wettability of the perovskite precursor solution on the carbazole surface. Here a self‐assembled bilayer (SAB) comprising a covalent monolayer (Br‐2PACz) and a noncovalent wetting layer (4CzNH3I) as the HTL in a Cs0.25FA0.75Sn0.5Pb0.5I3 perovskite solar cell is proposed. It is demonstrated that the wetting layer completely solves the problem due to the higher polarity of the surface and, furthermore, the ammonium groups help in the passivation of trap states at the buried SAB/perovskite interface. The introduction of the SAB enhances the device reproducibility with an average efficiency of 18.98 ± 0.28% (19.45% for the best device), compared to 11.54 ± 9.36% (19.34% for the best device) for the SAM‐only devices. Furthermore, the improved perovskite processability on the SAB helps to increase the reproducibility of larger size device, where, a 12.5% efficiency for a 0.8 cm2 active area device compared to 0.68% for the best SAM‐based solar cell is demonstrated. Finally, the device's operational stability is also improved to 358 hours (T80%), compared to 220 hours for the SAM‐based solar cell.

An analysis is provided of MA-free Sn/Pb-perovskite solar cells fabricated using PEDOT:PSS, 2PACz, and Br-2PACz as the HTL. An efficiency of 19.51% has been reached by using Br-2PACz with improved device stability, thanks to suppressed recombination.

This paper describes the effectiveness of donor− acceptor (D-A) conjugated polymers to disperse and select for semiconducting single-walled carbon nanotubes (s-SWCNTs) when enhanced by the inclusion of polar oligoethylene glycolbased side chains, without altering the D−A backbone. We designed and synthesized two sets of naphthalenediimide(NDI)alt-bithiophene(T2)-based conjugated polymers with one of two alkyl side chains (decyl and dodecyl chains) of different lengths and with or without polar triethylene glycol side chains. The resulting low-band-gap copolymers all effectively disperse and select for s-SWCNT, but the inclusion of polar side chains enhances the interactions between the polymer backbone and the walls of the s-SWCNTs relative to the polymers with only alkyl side chains. As a result, the wrapping and selection efficiency of the polymer-SWCNT systems with polar side chains are both significantly enhanced. We further optimized the binding energy and surface coverage by combining glycol ether and dodecyl side chains to maximize wrapping efficiency, leading to a field-effect mobility of 2.82 cm 2 V −1 s −1 and on/off current ratios of ∼2 × 10 7 in polymer-wrapped SWCNTs. Our results provide insight into the role of the side-chain interactions in the polymer wrapping and dispersion technique, and, because we focus on manipulating side chains, they can be generalized for other conjugated polymer backbones.

Two terminal passive devices are regarded as one of the promising candidates to solve the processor‐memory bottleneck in the Von Neumann computing architectures. Many different materials are used to fabricate memory devices, which have the potential to act as synapses in future neuromorphic electronics. Metal halide perovskites are attractive for memory devices as they display high density of defects with a low migration barrier. However, to become promising for a future neuromorphic technology, attention should be paid on non‐toxic materials and scalable deposition processes. Herein, it is reported for the first time the successful fabrication of resistive memory devices using quasi‐2D tin–lead perovskite of composition (BA)2MA4(Pb0.5Sn0.5)5I16 by blade coating. The devices show typical memory characteristics with excellent endurance (2000 cycles), retention (105 s), and storage stability (3 months). Importantly, the memory devices successfully emulate synaptic behaviors such as spike‐timing‐dependent plasticity, paired‐pulse facilitation, short‐term potentiation, and long‐term potentiation. A mix of slow (ionic) transport and fast (electronic) transport (charge trapping and de‐trapping) is proven to be responsible for the observed resistive switching behavior.

Conjugated polymers with narrow band gaps are particularly useful for sorting and discriminating semiconducting single-walled carbon nanotubes (s-SWCNT) due to the low charge carrier injection barrier for transport. In this paper, we report two newly synthesized narrow-band-gap conjugated polymers (PNDITEG-TVT and PNDIC8TEG-TVT) based on naphthalene diimide (NDI) and thienylennevinylene (TVT) building blocks, decorated with different polar side chains that can be used for dispersing and discriminating s-SWCNT. Compared with the mid-band-gap conjugated polymer PNDITEG-AH, which is composed of naphthalene diimide (NDI) and head-to-head bithiophene building blocks, the addition of a vinylene linker eliminates the steric congestion present in head-to-head bithiophene, which promotes backbone planarity, extending the π-conjugation length and narrowing the band gap. Cyclic voltammetry (CV) and density functional theory (DFT) calculations suggest that inserting a vinylene group in a head-to-head bithiophene efficiently lifts the highest occupied molecular orbital (HOMO) level (−5.60 eV for PNDITEG-AH, −5.02 eV for PNDITEG-TVT, and −5.09 eV for PNDIC8TEG-TVT). All three polymers are able to select for s-SWCNT, as evidenced by the sharp transitions in the absorption spectra. Field-effect transistors (FETs) fabricated with the polymer:SWCNT inks display p-dominant properties, with higher hole mobilities when using the NDI-TVT polymers as compared with PNDITEG-AH (0.6 cm2 V–1 s–1 for HiPCO:PNDITEG-AH, 1.5 cm2 V–1 s–1 for HiPCO:PNDITEG-TVT, and 2.3 cm2 V–1 s–1 for HiPCO:PNDIC8TEG-TVT). This improvement is due to the better alignment of the HOMO level of PNDITEG-TVT and PNDIC8TEG-TVT with that of the dominant SWCNT specie.