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All‐inorganic n‐i‐p perovskite solar cells (PSCs) using doped Spiro‐OMeTAD as hole transport material (HTM) suffer from photothermal stability due to ionic diffusion and radical‐induced degradation by the dopants. In this article, dopant‐free starlike molecule (N2, N2‐bis(4‐(bis(4‐methoxyphenyl)amino)phenyl)‐N5,N5‐bis(4‐methoxyphenyl)pyridine‐2,5‐diamine (BD)) is synthesized to engineer the stacking properties and delivered higher hole mobility than doped Spiro‐OMeTAD (3.2 × 10−4 versus 1.76 × 10−4 cm2 V−1 s−1) as dopant‐free HTM. Starlike BD HTM has a twisted acceptor unit and strong dipole, forming crystalline and ordered packing film to ensure intramolecular charge transfer and improve mobility. The BD CsPbI3 PSCs deliver the maximum efficiency of 19.19%, which is the highest performance for all‐inorganic PSCs based on dopant‐free HTMs. Meanwhile, the ordered molecules‐packing blocks the migration channel of I− ions to metal electrodes and improves the device stability. BD‐based devices maintain more than 93% and 80% of the initial efficiency after 85 °C storage for 35 days and maximum power point (MPP) tracking at 85 °C for 1000 h, respectively. [ABSTRACT FROM AUTHOR]

The inadequate hole injection limits the efficiency and lifetime of the blue quantum dot light‐emitting diodes (QLEDs), which severely hampers their commercial applications. Here a new discotic molecule of 3,6,10,11‐tetrakis(pentyloxy)triphenylene‐2,7‐diyl bis(2,2‐dimethylpropanoate) (T5DP‐2,7) is introduced, in which the hole transport channels with superior hole mobility (2.6 × 10–2 cm2 V–1 s–1) is formed by stacking. The composite hole transport material (HTM) is prepared by blending T5DP‐2,7 with the cross‐linked 4,4′‐ bis(3‐vinyl‐9H‐carbazol‐9‐yl)‐1,1′biphenyl (CBP‐V) which shows the deep highest occupied molecular orbital energy level. The increased hole mobility of the target composite HTM from 10–4 to 10–3 cm2 V–1 s–1 as well as the stepwise energy levels facilitates the hole transport, which would be beneficial for more balanced carrier injection. This composite hole transport layer (HTL) has improved the deep‐blue‐emission performances of Commission International de I'Eclairage of (0.14, 0.04), luminance of 44080 cd m−2, and external quantum efficiency of 18.59%. Furthermore, when L0 is 100 cd m−2, the device lifetime T50 is extended from 139 to 502 h. The state‐of‐the‐art performance shows the successful promotion of the high‐efficiency for deep blue QLEDs, and indicates that the optimizing HTL by discotic molecule stacking can serve as an excellent alternative for the development of HTL in the future. [ABSTRACT FROM AUTHOR]

CuI is a wide bandgap p-type transparent conductor with promising optoelectronic properties. However, conventional CuI films prepared through the iodination of Cu films exhibit rough surface, poor stability and excessively high hole concentration, hindering its application. Herein, we introduce CuI−Ga 2 O 3 composite films as a substitution to overcome the shortcomings of pure CuI. During the iodination process, Ga 2 O 3 hindered the mobility of CuI grain boundaries, resulting in small grain size and low surface roughness. After the charge re-equilibrium and low-energy carrier filtering at the interface between Ga 2 O 3 and CuI, the hole concentration in the films decreased by an order of magnitude. Due to the interface effect of Ga 2 O 3 at the grain boundaries of CuI, the hole mobility increased by 5 times, and the conductivity improved by 53%. The ultra-wide band gap of Ga 2 O 3 enhanced the transmittance of CuI films in short wavelength region. Ga 2 O 3 served to passivate the grain boundaries of CuI, preventing the oxidation of CuI and the loss of iodine, consequently improving the stability of the films. This work will deepen the understanding of the failure and hole transport mechanisms of CuI films. • The second phase Ga 2 O 3 inhibits the movement of CuI grain boundaries. • Ga 2 O 3 reduces the surface roughness of CuI films. • CuI−Ga 2 O 3 films have lower hole concentration, higher conductivity and hole mobility. • CuI−Ga 2 O 3 films exhibit better stability in ambient than pure CuI films. [ABSTRACT FROM AUTHOR]

Abstract Semi-conductive alumina/nano-carbon ceramic composite with high hole mobility is fabricated by gel-casting and reductive sintering. The hole mobility observed in the fabricated composite is 80-fold higher than the previously reported alumina/graphene composite. Such superior semi-conductive performance of the alumina/nano-carbon composite can be attributed to the homogenous electrically conductive path induced by nano-carbon with well-controlled graphite structure formed during fabrication process. In addition, the influence of sintering temperature on the structure of nano-carbon as well as its relation to the semi-conductive properties of composite are systemically investigated. [ABSTRACT FROM AUTHOR]

• PCN1 and PCN2 were constructed with dicyanobenzotriazole as the acceptor block. • PCN2 with strong absorption and high hole mobility. • Organic solar cells based on PCN2:Y6 reached a high PCE of 15.20%. Two halogen-free donor polymers PCN1 (zigzag-shape backbone) and PCN2 (linear-shape backbone) were constructed with dicyanobenzotriazole as the acceptor (A) block. Their absorption, energy levels, charge transport properties, and applications as donors in organic solar cells (OSCs) were thoroughly investigated. PCN2 with strong absorption at 400–700 nm, maximum extinction coefficient of up to 8.67 × 104 M−1 cm−1, low highest occupied molecular orbital (-5.50 eV), and the high hole mobility (1.42 × 10−3 cm2 V−1 s−1) is an excellent donor polymer. The OSCs based on PCN2:Y6 reached a high PCE of 15.20% without the addition of any additives and any post-treatment, with an open-circuit voltage (V oc) of 0.862 V, which is by far the highest PCE among OSCs with donor polymers based on benzotriazole derivatives, and it is also one of the highest V oc reported for binary OSCs matched to Y6 in halogen-free donor polymers. The measurements of atomic force microscopy, transmission electron microscopy, and grazing-incidence wide-angle X-ray scattering show that PCN2 has a more orderly arrangement and stronger π-π stacking, and the PCN2:Y6 device exhibits better charge transport, higher and more balanced carrier mobility, less exciton recombination loss, suitable phase separation size, which lead to its higher photovoltaic performance. [ABSTRACT FROM AUTHOR]

Abstract: We have developed an effective synthetic route for 2,9-dibromopentacene, opening up new possibilities for future derivatization of pentacene. We also present the fundamental properties. Thin-film and single-crystal field-effect transistor results demonstrate a decrease in apparent charge transport efficiency with decreasing symmetry. The trend in symmetry was further correlated to single-crystal structural analysis, which implied that reduction in symmetry also reduced solid-state order. It is likely that this reduction in order is responsible for the diminished performance in the solid-state films and crystal, despite a reduction in overall tilt angle of the molecules relative to one another. Combined with previous studies, this work provides a more complete perspective on the interplay of symmetry, energetic, and intermolecular interactions in the macroscopic properties of solid-state organic electronic materials. [Copyright &y& Elsevier]

The strained Si layer has been grown on the relaxed 3C–SiC virtual substrate by a hot-wall low-pressure chemical vapor deposition (LPCVD) system. The relaxed SiC virtual substrate was grown on Si(1 1 1) substrate by LPCVD and the crystal quality of the layer is characterized by X-ray diffraction and Fourier transform infrared absorption spectroscopy. It is apparent to find three regions in the Auger electron spectroscopy depth profile graph of the sample, which refer to the cap Si layer, the relaxed 3C–SiC virtual substrate and the Si(1 1 1) substrate, respectively. The bonding states of the relaxed 3C–SiC virtual substrate in the sample are analyzed by X-ray photoelectron spectroscopy. The Raman spectra of the sample indicate the cap Si layer is strained. A high hole Hall mobility value of 889 cm2/V s (300 K) is obtained in the strained Si layer, which is due to the in-plane compressive biaxial strain in this layer. [Copyright &y& Elsevier]

[Display omitted] • Trifluoropropoxy group as a hydrophobic terminal unit has been introduced to HTM. • Asymmetric SGT-405s(C 2 ,CF 3) exists in amorphous state and possesses high T g. • SGT-405s(C 2 ,CF 3) exhibits better hydrophobicity than spiro-OMeTAD. • PSC with SGT-405s(C 2 ,CF 3) showed a better PCE (20.14%) than spiro-OMeTAD (18.97%). • PSC with SGT-405s(C 2 ,CF 3) showed enhanced moisture and thermal stability. For highly efficient and stable perovskite solar cells (PSCs), small molecular hole transporting materials (HTMs) with high glass transition temperature, hydrophobicity, excellent film-formation and excellent hole mobility is highly desireable. However, developing a single molecule, which could meet all the above mention properties, is challenging. Herein, novel small molecules were design and synthesized, which show a suitable HOMO energy level and fulfill the above metioned properties simultaneously. For this purpose, we incorporate a hydrophobic trifluoropropoxy-terminal group to diphenylamine in SGT-405(3,6), a carbazole-based promising non-spiro-type small molecular HTM with excellent performance and low-cost, leading to two new HTMs (SGT-405s(C 2 ,CF 3) and SGT-405d(C 2 ,CF 3)). Among them SGT-405s(C 2 ,CF 3) showed an excellent hole mobility of 3.32 × 10–4 cm2 V−1 s−1, a remarkable high T g of 183 ℃ and increased water contact angle of 87° compared to that of spiro OMeTAD (77.7°). Due to these superior properties, compared to those of spiro-OMeTAD, PSCs based on SGT-405s(C 2 ,CF 3) showed a remarkable power conversion efficiency (PCE) of 20.14%, which is higher than that of spiro-OMeTAD (18.97%), together with enhanced long-term and thermal stability. Our work revealed for the first time that trifluoropropoxy is a potential terminal group and an effective strategy for the design of new HTMs possessing superior properties in terms of glass transition temperature, hydrophobicity and film formation, for realizing efficient PSCs with enhanced moisture and thermal stability, simultaneously. [ABSTRACT FROM AUTHOR]

The novel and appropriate molecular design for polymer donors are playing an important role in realizing high-efficiency and high stable polymer solar cells (PSCs). In this work, four conjugated polymers (PIDT-O, PIDTT-O, PIDT-S and PIDTT-S) with indacenodithiophene (IDT) and indacenodithieno [3,2-b]thiophene (IDTT) as the donor units, and alkoxy-substituted benzoxadiazole and benzothiadiazole derivatives as the acceptor units have been designed and synthesized. Taking advantages of the molecular engineering on polymer backbones, these four polymers showed differently photophysical and photovoltaic properties. They exhibited wide optical bandgaps of 1.88, 1.87, 1.89 and 1.91 eV and quite impressive hole mobilities of 6.01 × 10−4, 7.72 × 10−4, 1.83 × 10−3, and 1.29 × 10−3 cm2 V−1 s−1 for PIDT-O, PIDTT-O, PIDT-S and PIDTT-S, respectively. Through the photovoltaic test via using PIDT-O, PIDTT-O, PIDT-S and PIDTT-S as donor materials and [6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM) as acceptor materials, all the PSCs presented the high open circuit voltages (Vocs) over 0.85 V, whereas the PIDT-S and PIDTT-S based devices showed higher power conversion efficiencies (PCEs) of 5.09% and 4.43%, respectively. Interestingly, the solvent vapor annealing (SVA) treatment on active layers could improve the fill factors (FFs) extensively for these four polymers. For PIDT-S and PIDTT-S, the SVA process improved the FFs exceeding 71%, and ultimately the PCEs were increased to 6.05%, and 6.12%, respectively. Therefore, this kind of wide band-gap polymers are potentially candidates as efficient electron-donating materials for constructing high-performance PSCs. [ABSTRACT FROM AUTHOR]