This review summarizes recent advancements in various orientation techniques for conjugated polymers for use in high performance organic field effect transistors.

Tin−lead (Sn−Pb)-based perovskite solar cells (PSCs) still exhibit inferior power conversion efficiency (PCE) compared to their pure Pb counterparts because of high voltage loss (V L ) and high photocurrent loss in the infrared region. This study explores that a small amount of cesium ion (Cs + ) incorporation in the lattice of Sn−Pb perovskite can reduce the relative lattice strain, which in turn decreases the V L less than 0.50 V. Moreover, surface and bulk trap densities also seem to be reduced by Cs + addition, as concluded by thermally stimulated current measurements and increased carrier lifetime by photoluminescence study. It was discovered that a small amount of Cs + lowered the Urbach energy, which can be used as a signature to optimize the optoelectronic and the photovoltaic properties of multication perovskite materials. This study further demonstrates that a high external quantum efficiency (∼80% at 900 nm) can be obtained with fluorine-doped tin oxide (FTO) glass rather than frequently used indium tin oxide (ITO) glass. The strategies employed in the work improved the open-circuit voltage to 0.81 V and gave a photocurrent density of >30 mA/cm 2 and a PCE of >20% using a band gap of 1.27 eV.

A synergistic approach to enhance charge‐carrier transport in organic semiconductors along with facile solution processing and high performance is crucial for the advancement of organic electronics. The floating film transfer method (FTM) is used as a facile and cost‐effective method for the fabrication of large‐scale, uniform, highly oriented poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (pBTTT C‐14) films under ambient conditions. Utilization of such oriented films as the active semiconducting layer in organic field‐effect transistors (OFETs) results in highly anisotropic charge‐carrier transport. Highly oriented, FTM‐processed pBTTT C‐14 thin films are characterized by polarized electronic absorption and Raman spectroscopy, atomic force microscopy, out‐of‐plane X‐ray diffraction, and grazing incident X‐ray diffraction (GIXD) measurements. The GIXD data indicate an edge‐on orientation, which is highly desirable for planar devices such as OFETs. OFETs built using the oriented films show a mobility anisotropy of 10 and the highest mobility is 1.24 cm2 V−1 s−1 along the backbone orientation, which is among the highest value reported for this class of materials using a similar device configuration.

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Unavoidable defects in grain boundaries (GBs) are detrimental and critically influence the organometal halide perovskite performance and stability. To address this issue, semiconducting molecules have been employed to passivate traps along perovskite GBs. Here, we designed and synthesized three squaraine molecules (SQ) with zwitterionic structure to interact with under-coordinated Pb2+ and passivate Pb–I antisite defects. Density functional theory calculation shows symmetric O atoms could coordinate with perovskite grains simultaneously, resulting in continuous charge distribution at the SQ–perovskite interface. The energetic traps distribution in CH3NH3PbI3 perovskite is influenced significantly by the interaction between SQ and perovskite as analyzed by thermally stimulated current, in which the deep-level defects are considerably reduced due to efficient SQ passivation. In addition, we explore how SQ molecules with different energy offset affect the charge extraction, which is suggested to facilitate exciton separation at the perovskite–SQ interface. These benefits lead to enhanced perovskite efficiency from 15.77 to 18.83% with the fill factor approaching 80%, which is among the highest efficiency reported for MAPbI3 solar cells fabricated in an ambient environment at 60% relative humidity (RH). Considerable retardation of perovskite device degradation was achieved, retaining 90% of initial efficiency when kept 600 h at 60 ± 5% RH.