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Abstract A dopant-free hole transport layer with high mobility and a low-temperature process is desired for optoelectronic devices. Here, we study a metal–organic framework material with high hole mobility and strong hole extraction capability as an ideal hole transport layer for perovskite solar cells. By utilizing lifting-up method, the thickness controllable floating film of Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 at the gas–liquid interface is transferred onto ITO-coated glass substrate. The Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 film demonstrates high compactness and uniformity. The root-mean-square roughness of the film is 5.5 nm. The ultraviolet photoelectron spectroscopy and the steady-state photoluminescence spectra exhibit the Ni3(HITP)2 film can effectively transfer holes from perovskite film to anode. The perovskite solar cells based on Ni3(HITP)2 as a dopant-free hole transport layer achieve a champion power conversion efficiency of 10.3%. This work broadens the application of metal–organic frameworks in the field of perovskite solar cells. Graphical Abstract

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]

Abstract 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.

A dopant-free hole transport layer with high mobility and a low-temperature process is desired for optoelectronic devices. Here, we study a metal–organic framework material with high hole mobility and strong hole extraction capability as an ideal hole transport layer for perovskite solar cells. By utilizing lifting-up method, the thickness controllable floating film of Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 at the gas–liquid interface is transferred onto ITO-coated glass substrate. The Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 film demonstrates high compactness and uniformity. The root-mean-square roughness of the film is 5.5 nm. The ultraviolet photoelectron spectroscopy and the steady-state photoluminescence spectra exhibit the Ni3(HITP)2 film can effectively transfer holes from perovskite film to anode. The perovskite solar cells based on Ni3(HITP)2 as a dopant-free hole transport layer achieve a champion power conversion efficiency of 10.3%. This work broadens the application of metal–organic frameworks in the field of perovskite solar cells. [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]

The p‐type nanowire field‐effect transistor (FET) with a SiGe shell channel on a Si core is optimally designed and characterized using in‐depth technology computer‐aided design (TCAD) with quantum models for sub‐10‐nm advanced logic technology. SiGe is adopted as the material for the ultrathin shell channel owing to its two primary merits of high hole mobility and strong Si compatibility. The SiGe shell can effectively confine the hole because of the large valence‐band offset (VBO) between the Si core and the SiGe channel arranged in the radial direction. The proposed device is optimized in terms of the Ge shell channel thickness, Ge fraction in the SiGe channel, and the channel length (Lg) by examining a set of primary DC and AC parameters. The cutoff frequency (fT) and maximum oscillation frequency (fmax) of the proposed device were determined to be 440.0 and 753.9 GHz when Lg is 5 nm, respectively, with an intrinsic delay time (τ) of 3.14 ps. The proposed SiGe‐shell channel p‐type nanowire FET has demonstrated a strong potential for low‐power and high‐speed applications in 10‐nm‐and‐beyond complementary metal‐oxide‐semiconductor (CMOS) technology.

The p‐type nanowire field‐effect transistor (FET) with a SiGe shell channel on a Si core is optimally designed and characterized using in‐depth technology computer‐aided design (TCAD) with quantum models for sub‐10‐nm advanced logic technology. SiGe is adopted as the material for the ultrathin shell channel owing to its two primary merits of high hole mobility and strong Si compatibility. The SiGe shell can effectively confine the hole because of the large valence‐band offset (VBO) between the Si core and the SiGe channel arranged in the radial direction. The proposed device is optimized in terms of the Ge shell channel thickness, Ge fraction in the SiGe channel, and the channel length (Lg) by examining a set of primary DC and AC parameters. The cutoff frequency (fT) and maximum oscillation frequency (fmax) of the proposed device were determined to be 440.0 and 753.9 GHz when Lg is 5 nm, respectively, with an intrinsic delay time (τ) of 3.14 ps. The proposed SiGe‐shell channel p‐type nanowire FET has demonstrated a strong potential for low‐power and high‐speed applications in 10‐nm‐and‐beyond complementary metal‐oxide‐semiconductor (CMOS) technology. [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.

It has been shown that the base-initiated cyclo-oligomerisation of phthalonitriles is favoured by bulky α-substituents making it possible to obtain the metal-free phthalocyanine directly and in high yield. The phthalocyanine with eight α-isoheptyl substituents gives a high time-of-flight hole mobility of 0.14 cm2·V−1·s−1 within the temperature range of the columnar hexagonal phase, that is 169–189 °C.

• 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]

[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]

It has been shown that the base-initiated cyclo-oligomerisation of phthalonitriles is favoured by bulky α-substituents making it possible to obtain the metal-free phthalocyanine directly and in high yield. The phthalocyanine with eight α-isoheptyl substituents gives a high time-of-flight hole mobility of 0.14 cm(2)·V(-1)·s(-1) within the temperature range of the columnar hexagonal phase, that is 169-189 °C.