One effective strategy to improve the performance of perovskite solar cells (PSCs) is to develop new hole transport layers (HTLs). In this work, a simple polyelectrolyte HTL, copper (II) poly(styrene sulfonate) (Cu:PSS), which comprises easily reduced Cu2+ counter‐ions with an anionic PSS polyelectrolyte backbone is investigated. Photoelectron spectroscopy reveals an increase in the work function of the anode and upward band bending effect upon incorporation of Cu:PSS in PSC devices. Cu:PSS shows a synergistic effect when mixed with polyethylenedioxythiophene: polystyrenesulfonate (PEDOT:PSS) in various proportions and results in a decrease in the acidity of PEDOT:PSS as well as reduced hysteresis in completed devices. Cu:PSS functions effectively as a HTL in PSCs, with device parameters comparable to PEDOT:PSS, while mixtures of Cu:PSS with PEDOT:PSS shows greatly improved performance compared to PEDOT:PSS alone. Optimized devices incorporating Cu:PSS/PEDOT:PSS mixtures show an improvement in efficiency from 14.35 to 19.44% using a simple CH3NH3PbI3 active layer in an inverted (P‐I‐N) geometry, which is one of the highest values yet reported for this type of device. It is expected that this type of HTL can be employed to create p‐type contacts and improve performance in other types of semiconducting devices as well.

The electrical and optical properties of inorganic–organic hybrid light emitting transistors (HLETs) are investigated, which are fabricated using the n‐type semiconductor zinc‐oxynitride (ZnON) as an electron transporting layer and the poly(p‐phenylene vinylene)‐based copolymer, Super Yellow (SY), as the light emitting layer. Additionally, the influence of various source (S)–drain (D) electrodes (Al, Ag, and Au) with different work functions (WFs) (4.1, 4.6, and 5.1 eV, respectively) on the performance of HLETs is studied. In order to increase the rate of hole injection from the metal electrodes and increase hole accumulation at the emissive layer, the use of a molybdenum oxide (MoOx) interlayer is also investigated. As a result, optimized devices using MoOx/Au hole injecting electrodes yield high brightness of up to 3.04 × 104 cd∙m−2 at a low threshold voltage of 4.79 V. This study provides valuable information about the role of the WF of S–D electrodes in HLETs, which may be exploited to improve the device performance of optoelectronic devices in the future.

We have investigated the field-effect transistor characteristics of a series of isoindigo based donor–acceptor–donor small molecules via solvent additives.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/aelm.201700184. Organic SemiconductorsOrganic field-effect transistors (OFETs) promise to play critical roles in the future of portable electronic devices, such as flexible displays, smart cards, and radio-frequency identification tags. [1,2] Since their first report some 30 years ago, [3] the performance of OFETs has reached hole mobilities of up to 23 cm 2 V −1 s −1 using polymeric semiconductors OFETs or 43 cm 2 V −1 s −1 in the case of small molecule-based p-type