A new method to synthesize an electron-rich building block cyclopentadithienothiophene (9H-thieno-[3,2-b]thieno[2″,3″:4′,5′]thieno[2′,3′:3,4]cyclopenta[1,2-d]thiophene, CDTT) via a facile aromatic extension strategy is reported. By combining CDTT with 1,1-dicyanomethylene-3-indanone endgroups, a promising nonfullerene small molecule acceptor (CDTTIC) is prepared. As-cast, single-junction nonfullerene organic solar cells based on PFBDB-T: CDTTIC blends exhibit very high short-circuit currents up to 26.2 mA cm−2 in combination with power conversion efficiencies over 11% without any additional processing treatments. The high photocurrent results from the near-infrared absorption of the CDTTIC acceptor and the well-intermixed blend morphology of polymer donor PFBDB-T and CDTTIC. This work demonstrates a useful fused ring extension strategy and promising solar cell results, indicating the great potential of the CDTT derivatives as electron-rich building blocks for constructing high-performance small molecule acceptors in organic solar cells.

Mixed-cation lead mixed-halide perovskites are employed as the photoactive material in single-layer solution-processed photodetectors fabricated with coplanar asymmetric nanogap Al–Au and indium tin oxide–Al electrodes. The nanogap electrodes, bearing an interelectrode distance of ≈10 nm, are patterned via adhesion lithography, a simple, low-cost, and high-throughput technique. Different electrode shapes and sizes are demonstrated on glass and flexible plastic substrates, effectively engineering the device architecture, and, along with perovskite film and material optimization, paving the way toward devices with tunable operational characteristics. The optimized coplanar nanogap junction perovskite photodetectors show responsivities up to 33 A W−1, specific detectivity on the order of 1011 Jones, and response times below 260 ns, while retaining a low dark current (0.3 nA) under −2 V reverse bias. These values outperform the vast majority of perovskite photodetectors reported so far, while avoiding the complicated fabrication steps involved in conventional multilayer device structures. This work highlights the promising potential of the proposed asymmetric nanogap electrode architecture for application in the field of flexible optoelectronics.

Molecular doping is a powerful yet challenging technique for enhancing charge transport in organic semiconductors (OSCs). While there is a wealth of research on p-type dopants, work on their n-type counterparts is comparatively limited. Here, reported is the previously unexplored n-dopant (12a,18a)-5,6,12,12a,13,18,18a,19-octahydro-5,6-dimethyl- 13,18[1′,2′]-benzenobisbenzimidazo [1,2-b:2′,1′-d]benzo[i][2.5]benzodiazo-cine potassium triflate adduct (DMBI-BDZC) and its application in organic thin-film transistors (OTFTs). Two different high electron mobility OSCs, namely, the polymer poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8- bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2′-bithiophene)] and a small-molecule naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) are used to study the effectiveness of DMBI-BDZC as a n-dopant. N-doping of both semiconductors results in OTFTs with improved electron mobility (up to 1.1 cm2 V−1 s−1), reduced threshold voltage and lower contact resistance. The impact of DMBI-BDZC incorporation is particularly evident in the temperature dependence of the electron transport, where a significant reduction in the activation energy due to trap deactivation is observed. Electron paramagnetic resonance measurements support the n-doping activity of DMBI-BDZC in both semiconductors. This finding is corroborated by density functional theory calculations, which highlights ground-state electron transfer as the main doping mechanism. The work highlights DMBI-BDZC as a promising n-type molecular dopant for OSCs and its application in OTFTs, solar cells, photodetectors, and thermoelectrics.

The astonishing recent progress in the field of metal oxide thin-film transistors (TFTs) and their debut in commercial displays is accomplished using vacuum-processed multicomponent oxide semiconductors. However, emulating this success with their solution-processable counterparts poses numerous scientific challenges. Here, the development of high mobility n-channel TFTs based on ultrathin (<10 nm) alternating layers of In2O3 and ZnO that are sequentially deposited to form heterojunction and superlattice channels is reported. The resulting TFTs exhibit high electron saturation mobility (13 cm2 V−1 s−1), excellent current on/off ratios (>108) with nearly zero onset voltages and hysteresis-free operation despite the low temperature processing (≤200 °C). The enhanced performance is attributed to the formation of a quasi-2D electron gas-like system at the In2O3/ZnO heterointerface due to the conduction band offset. It is shown that altering the oxide deposition sequence has an adverse effect on electron transport due to formation of trap states. Optimized multilayer TFTs are shown to exhibit improved bias-stress stability compared to single-layer TFTs. Modulating the electron concentration within the superlattice channel via selective n-doping of the ZnO interlayers leads to almost 100% saturation mobility increase (≈25 cm2 V−1 s−1) even when the TFTs are fabricated on flexible plastic substrates.

Parasitic absorption in transparent electrodes is one of the main roadblocks to enabling power conversion efficiencies (PCEs) for perovskite-based tandem solar cells beyond 30%. To reduce such losses and maximize light coupling, the broadband transparency of such electrodes should be improved, especially at the front of the device. Here, the excellent properties of Zr-doped indium oxide (IZRO) transparent electrodes for such applications, with improved near-infrared (NIR) response, compared to conventional tin-doped indium oxide (ITO) electrodes, are shown. Optimized IZRO films feature a very high electron mobility (up to ≈77 cm2 V−1 s−1), enabling highly infrared transparent films with a very low sheet resistance (≈18 Ω −1 for annealed 100 nm films). For devices, this translates in a parasitic absorption of only ≈5% for IZRO within the solar spectrum (250–2500 nm range), to be compared with ≈10% for commercial ITO. Fundamentally, it is found that the high conductivity of annealed IZRO films is directly linked to promoted crystallinity of the indium oxide (In2O3) films due to Zr-doping. Overall, on a four-terminal perovskite/silicon tandem device level, an absolute 3.5 mA cm−2 short-circuit current improvement in silicon bottom cells is obtained by replacing commercial ITO electrodes with IZRO, resulting in improving the PCE from 23.3% to 26.2%.

To realize multifunctional devices at the wafer scale, the growth process of monolayer (ML) 2D semiconductors must meet two key requirements: 1) growth of continuous and homogeneous ML film at the wafer scale and 2) controllable tuning of the properties of the ML film. However, there is still no growth method available that fulfills both of these criteria. Here, the first report is presented on the preparation of continuous and uniform ML MoS2 films through a two-step process at the wafer scale. Unlike in previous ML MoS2 film growth processes, the ML MoS2 film can be uniformly modulated across the wafer in terms of material structure and composition, exciton state, and electronic transport performance. A significant result is that the high-quality wafer-scale ML MoS2 films realize superior electronic performance compared to reported two-step-grown films, and it even matches or exceeds reported ML MoS2 films prepared by other processes. The transistor performance of the optimized ML film achieves a field effect mobility of 10 to 30 cm2 V−1 s−1, an on/off current ratio of about 107, and hysteresis as low as 0.4 V.

The application of graphite anodes in potassium-ion batteries (KIB) is limited by the large variation in lattice volume and the low diffusion coefficient of potassium ions during (de)potassiation. This study demonstrates nitrogen-doped, defect-rich graphitic nanocarbons (GNCs) as high-performance KIB anodes. The GNCs with controllable defect densities are synthesized by annealing an ethylenediaminetetraacetic acid nickel coordination compound. The GNCs show better performance than the previously reported thin-walled graphitic carbonaceous materials such as carbon nanocages and nanotubes. In particular, the GNC prepared at 600 °C shows a stabilized capacity of 280 mAh g−1 at 50 mA g−1, robust rate capability, and long cycling life due to its high-nitrogen-doping, short-range-ordered, defect-rich graphitic structure. A high capacity of 189 mAh g−1 with a long cycle life over 200 cycles is demonstrated at a current density of 200 mA g−1. Further, it is confirmed that the potassium ion storage mechanism of GNCs is different from that of graphite using multiple characterization methods. Specifically, the GNCs with numerous defects provide more active sites for the potassiation process, which results in a final discharge product with short-range order. This study opens a new pathway for designing graphitic carbonaceous materials for KIB anodes.

Producing high efficiency solar cells without high-temperature processing or use of additives still remains a challenge with the two-step process. Here, the solution processing of MAPbI3 from PbI2 films in N,N-dimethylformamide (DMF) is investigated. In-situ grazing incidence wide-angle X-ray scattering (GIWAXS) measurements reveal a sol–gel process involving three PbI2-DMF solvate complexes—disordered (P0) and ordered (P1, P2)—prior to PbI2 formation. When the appropriate solvated state of PbI2 is exposed to MAI (methylammonium Iodide), it can lead to rapid and complete room temperature conversion into MAPbI3 with higher quality films and improved solar cell performance. Complementary in-situ optical reflectance, absorbance, and quartz crystal microbalance with dissipation (QCM-D) measurements show that dry PbI2 can take up only one third of the MAI taken up by the solvated-crystalline P2 phase of PbI2, requiring additional annealing and yet still underperforming. The perovskite solar cells fabricated from the ordered P2 precursor show higher power conversion efficiency (PCE) and reproducibility than devices fabricated from other cases. The average PCE of the solar cells is greatly improved from 13.2(±0.53)% (from annealed PbI2) to 15.7(±0.35)% (from P2) reaching up to 16.2%. This work demonstrates the importance of controlling the solvation of PbI2 as an effective strategy for the growth of high-quality perovskite films and their application in high efficiency and reproducible solar cells.

Over the past few decades, significant progress has been made in the field of photonic processing of electronic materials using a variety of light sources. Several of these technologies have now been exploited in conjunction with emerging electronic materials as alternatives to conventional high-temperature thermal annealing, offering rapid manufacturing times and compatibility with temperature-sensitive substrate materials among other potential advantages. Herein, recent advances in photonic processing paradigms of metal-oxide thin-film transistors (TFTs) are presented with particular emphasis on the use of various light source technologies for the photochemical and thermochemical conversion of precursor materials or postdeposition treatment of metal oxides and their application in thin-film electronics. The pros and cons of the different technologies are discussed in light of recent developments and prospective research in the field of modern large-area electronics is highlighted.

Zinc vacancy (VZn) is successfully introduced into 3D hierarchical ZnIn2S4 (3D-ZIS). The photo-electrochemical experiments demonstrate that the charge separation and carrier transfer are more efficient in the 3D-ZIS with rich VZn. Of note, for the first time, it is found that VZn can decrease the carrier transport activation energy (CTAE), from 1.14 eV for Bulk-ZIS (Bulk ZnIn2S4) to 0.93 eV for 3D-ZIS, which may provide a feasible platform for further understanding the mechanism of photocatalytic CO2 reduction. In situ Fourier transform infrared (FT-IR) results reveal that the presence of rich VZn ensures CO2 chemical activation, promoting single-electron reduction of CO2 to CO2 −. In addition, in situ FT-IR and CO2 temperature programmed desorption results show that VZn can promote the formation of surface hydroxyl. To the best of current knowledge, there are no reports on the photoreduction of CO2 simply by virtue of 3D-ZIS with VZn and few literature reports on the photocatalytic reduction of CO2 concerned with CTAE. Additionally, this work finds that surface hydroxyl may play a crucial role in the process of CO2 photoreduction. The work may provide some novel ways to ameliorate solar energy conversion performance and a better understanding of photoreaction mechanisms.