Studies on printable semiconductors and technologies have increased rapidly over recent decades, pioneering novel applications in many fields, such as energy, sensing, logic circuits, and information ...displays. The newest display technologies are already turning to metal oxide semiconductors, i.e., indium gallium zinc oxide, for the improvements needed to drive active matrix organic light‐emitting diodes. Convenience and portability will be realized with flexible and wearable displays in the future. This report summarizes recent progress on the development of solution‐processed thin film transistors, especially those deposited at low temperatures for next‐generation flexible smart displays. The first part provides an overview on the history and current status of displays. Then, recent advances in state‐of‐the‐art solution‐processed transistors based on different semiconductors are presented, including metal oxides, organic materials, perovskites, and carbon nanotubes. Finally, conclusions are drawn and the remaining challenges and future perspectives are discussed.
Semiconductor evolution has greatly promoted the development of high‐end displays over the past decades. Benefiting from the unique characteristics of low‐cost solution routes, recent progress in the development of solution‐processed thin film transistors (metal oxides, organics, carbon nanotubes, and perovskite) and their applications in next‐generation flexible smart displays are summarized. The challenges and prospectives for further development are also highlighted.
Attaining high quality perovskite films with enhanced morphology, high efficiency, and better stability is a great research challenge. Here, a side‐chain liquid crystalline polymer (SCLCP) is ...incorporated as a dopant into the perovskite film to achieve perovskite solar cells (PSCs) with high efficiency and long‐term stability. SCLCP doping increases the grain size in the crystalline perovskite film by controlled solvent evaporation and reduced grain boundaries, which slow the material degradation and reduce the charge recombination. Using this approach, the PSC power conversion efficiency (PCE) is significantly boosted from 18.0% (nondoped) to 20.63% for the SCLCP‐doped perovskite film with much improved air stability. Furthermore, the trap state density in the SCLCP‐doped films is decreased because the SCLCP effectively passivates the perovskite grain surface. Notably, the SCLCP appears to act as a bridge between grains for effective charge transfer from perovskite toward the electrode, which would partially explain the enhanced efficiency and stability.
A smart strategy of doping side‐chain liquid crystalline polymer (SCLCP) into perovskite films enhances the grain size in the crystalline perovskite film, reduces the grain boundaries and charge recombination, and thereby affords a power conversion efficiency of 20.63% in perovskite solar cells with negligible hysteresis and much improved stability.
Carbazoles constitute one of the most widely used donor moieties for organic semiconductors due to their excellent hole transport and high environmental stability. However, they are seldomly used in ...recent high performance donor–acceptor (D–A) copolymers. In the present study, a planar regular terpolymer, PCbisDPP, composed of carbazole and thiophene flanked bis‐diketopyrrolopyrrole (bis‐DPP) for application as an active layer for high‐performance organic devices is reported. Organic field‐effect transistors with PCbisDPP as the active layer exhibit field‐effect mobility up to 1.48 cm2 v−1 s−1, which to the best of the current knowledge corresponds to the highest hole mobility reported to date for carbazole‐based D–A polymers. The high mobility is achieved via a tailored polymer‐design resulting in high crystallinity and a strong aggregating property without sacrificing solubility. PCbisDPP is applied as an active donor material in organic photodiode with fullerene derivative PC61BM as an acceptor in a bulk heterojunction blend. Binary additive combinations (tetralin: 1,8‐diiodooxtane (3:3) v/v%) utilization achieves an impressive performance with an external quantum efficiency of 80%, an average responsivity of 309.1 mA W−1, and specific detectivity of 4.73 × 1011 Jones in the near infra‐red light region (730 nm) utilizing a simple single layer organic photodiode structure as ITO/PEDOT:PSS/PCbisDPP:PC61BM/LiF/Al.
Herein, a highly planar regular terpolymer, PCbisDPP, structurally composed of a carbazole and bis‐diketopyrrolopyrrole with thiophenes is reported for application as an active layer in high‐performance organic field effect transistors with a very high field effect mobility up to 1.48 cm2 V−1 s−1, and organic photodiode with an external quantum efficiency of 80% at infra‐red light region (730 nm).
Controlling the morphology of conjugated polymer film through careful selection of solvent is very important for facilitating charge transport in organic opto-electrical and electrical devices. In ...this report, we systematically study on a selection rule for optimum solvent choice to achieve highly aligned conjugated polymer chains with large ordered domain sizes for high performance organic field-effect transistors (OFETs) through various experimental analysis and Hansen solubility parameters. Three parameters: boiling point, solubility, and molecular interaction between conjugated polymer and solvents, are the most important to obtain optimum morphology. Similar molecular interaction values between solvent and conjugated polymer determined the formation of larger size ordered domain in films. High boiling point and relatively poor solubility solvents affect anisotropic film formation of conjugated polymer chains during off-center spin-coating. Considering these, large ordered domains with highly aligned diketopyrrolopyrrole thieno3,2-bthiophene (DPPT-TT) polymer chains were achieved by these important factors, and we demonstrate impressively high field-effect mobility ∼5.89 cm2 V−1 s−1 with low standard deviation (13%), which is the highest reported value so far for top-gate/bottom-contact DPPT-TT OFETs.
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•We study on a selection rule for optimum solvent for highly aligned conjugated polymer.•The highly aligned film is obtained by off-center spin coating of DPPT-TT in marginal solvent.•High mobility of 5.89 cm2 V−1 s−1 is achieved by diketopyrrolopyrrole based OFETs.
Although perovskite solar cells (PSCs) have achieved high power conversion efficiency (PCE) by utilizing 2,2′,7,7′-tetrakis(
N,N
′-di-p-methoxyphenylamine)-9,9′-Spirobifluorene (Spiro-OMeTAD) as hole ...transporting material (HTM), the reproducibility and stability of PSCs are still a pressing concern. Herein, we introduced a solvent processed organic-organic bilayer based on 2-(4-(7-(9,9-dimethylacridin-10(9H)-yl)-9,9-diethyl-9H-fluoren-2-yl)phenyl)-1-phenyl-1H-phenanthro9,10-dimidazole (AFpPPI) and Spiro-OMeTAD in layer to layer as HTM in PSCs. The devices configured with AFpPPI/Spiro-OMeTAD bilayer achieved a maximum PCE of 19.9% in mesoporous-TiO
2
(mp-TiO
2
) structure with perovskite absorber of Cs
0.05
Rb
0.05
(FAPbI
3
)
0.76
(MAPbBr
3
)
0.14
. The properties of the bilayer structure were analyzed with steady-state photoluminescence, ultra-violet photoelectron and impedance spectroscopy. The AFpPPI/Spiro-OMeTAD improved open-circuit voltage (
V
oc
) by lowering the quasi-Fermi energy level for holes and reducing the charge recombination, resulting in high
V
oc
(1.14 V in the champion cell) and high fill factor (FF) that lead to high PCE. The addition of AFpPPI layer improves the quality of Spiro-OMeTAD and provides pinhole-free film. Moreover, the stability is improved in controlled temperature and humid conditions. This work affords a new approach for commercial applications of PSCs with better stability.
Single wall carbon nanotubes (SWNT) have been a significant research topic as active layers for thin film transistors (TFTs) due to their high charge carrier mobility beyond that of crystalline ...silicon. In this study, we report an effective approach to achieve a very high field-effect mobility and on/off ratio for solution processed semiconducting SWNT TFTs, by selective doping through contact with a thin ferric chloride (FeCl
3
) dopant layer. The semiconducting layer is formed by a double spin coating of the highly purified (>99%) high pressure carbon mono oxide (HiPCO) SWNT sorted by wrapping of poly (3-dodecylthiophene-2,5-diyl) (P3DDT). In order to achieve effective hole injection from the top Au source electrode without increasing the off-state drain current, less purified (98-99%) SWNTs produced by the plasma discharge process sorted by wrapping of poly (9,9-di-n-dodecylfluorene) (PFDD) are formed on the top of HiPCO film. Significantly improved TFT performance is achieved by the insertion of a few nanometers of a FeCl
3
dopant layer at the semiconductor-contact interface. A significant high hole field-effect of 48.35 ± 3.11 cm
2
V
−1
s
−1
(bare: 6.18 ± 0.87 cm
2
V
−1
s
−1
) with a reasonable on/off current ratio of 10
5
, and low off current of ∼80 pA, are obtained by controlling the concentration of FeCl
3
dopant (thickness = 1.5 nm) at the contact. Mobility is improved further at 2.5 nm thickness of the FeCl
3
dopant layer resulting in a hole mobility of 177 ± 13.2 cm
2
V
−1
s
−1
, an on/off ratio of 7.4 × 10
3
, and off state current of 1.2 × 10
−9
A.
Semiconductor evolution has greatly promoted the development of high‐end displays over the past decades. In article number 1904588, Yong Xu, Yong‐Young Noh, and co‐workers summarize the recent ...progress in the development of solution‐processed thin‐film transistors with various functional inks including metal oxides, organics, carbon nanotubes, and perovskite and their applications in next‐generation flexible smart displays. The challenges and prospective for further development are also highlighted.
We study the effect of solvent and pre-aggregated solution formed in a binary solvent system to achieve high performance organic field-effect transistors (OFETs) with ...indacenodithiophene-co-benzothiadiazole (IDT-BT) polymer. To quantify the degree of pre-aggregation, we selected a binary solvent system consisting of a mixture of good (chloronaphthanlene (CN), bp = 259 °C) and bad (2-methoxyl ethanol (2-ME), bp = 124 °C) solvents with various mixing ratios from 0 to 30 v% with the help of a Hansen solubility parameters program. The formation of pre-aggregated IDT-BT polymer was identified in an 8:2 CN:2-ME solvent ratio via a red-shift in a UV–vis absorption spectrum. The off-center spin coated IDT-BT OFETs from 8:2 ratio (CN:2-ME) solution exhibited more than double the improvement in field effect mobility (μFET = 1.38 ± 0.19 cm2/Vs) due to efficient charge injection through the smooth semiconducting film surface fabricated by the off-center spin-coating process from the polymer pre-aggregate in the binary solvent system with an appropriate mixing ratio.
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•Effect of binary solvent for performance in IDT-BT based OFETs is investigated.•Twice improved field effect mobility of μFET = 1.38 ± 0.19 cm2/Vs is achieved.•This improvement is due to efficient charge injection through the smooth IDT-BT film surface.
Herein, the molecular structure variation effect in well-known PTB polymer series based on the performance of organic photodiode (OPD) is explained. PTB7, PTB7-Th, and rr-PTBS polymers, which ...comprise of the same molecular structure as thieno3,4-bthiophene (TT) and benzo1,2-b:4,5-b′dithiophene (BDT) but distinct structural alterations, are used as donor moieties with 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno2,3-d:2′,3′-d’-s-indaceno1,2-b:5,6-b’dithiophene (IT-4F) as a non-fullerene acceptor for the bulk heterojunction OPD active layer. Panchromatic spectra response at a broad spectrum from 300 to 900 nm was observed in the OPDs with the above-mentioned combination. The bulk heterojunction conventional OPD based on a relatively thin rr-PTBS:IT-4F active layer with 3 v/v% of 1,8-diiodooctane additive at a wavelength of 600 nm (red light region) showed superior performance with the highest specific detectivity in the range of ~1012 Jones, an average responsivity of 312.94 mA/W and EQE of ~73% at −2 V. In this study, a stronger lamellar stacking and a much-pronounced face-on orientation with enhanced morphology of rr-PTB:IT-4F blend film is ascribed to its superior device performance compared to others.
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•The effect of PTB polymers on the performance of OPD is investigated. Panchromatic response from 300 to 900 nm was observed.•The bulk heterojunction OPD based on rr-PTBS:IT-4F with 3 v/v% of 1,8-diiodooctane additive showed superior performance.•With the wavelength of 600 nm (red light), highest specific detectivity of ~1012 Jones and EQE of ~73% at −2 V was observed.
Recent research has focused on increasing the open-circuit voltage (VOC) and current density (JSC) of perovskite solar cells (PSCs) by introducing p- or n-type dopants with higher electronegativity ...than Ti into the TiO2 electron transport layer (ETL). However, these kinds of dopant create undesired charge traps that hinder charge transport through TiO2. Therefore, the improvement in VOC is often accompanied by an undesired current density–voltage (J–V) hysteresis problem. Herein, we demonstrate that the introduction of 4-chlorobenzoic acid (4-ClBA-TiO2) dopant into TiO2 not only overcomes the J–V hysteresis issue but also increases the VOC, JSC and power conversion efficiency (PCE) in mesoscopic PSCs. Also, the material shown the better device performance compared to the state-of-art ETL, with the 4-CLBA-TiO2. We speculate that the interaction between the 4-ClBA and the perovskite interface is more selective for electrons. Further the 4-ClBA-TiO2 electron mobility has been improved 1.9 times compared with TiO2. As a result, for mesoscopic PSCs, the doping of 4-ClBA-TiO2 increases the efficiency from 18.23% to 20.22%, while the hysteresis is largely reduced from 20.2% to 1.5%. To the best of our knowledge, this is the first report using the spin coating blocking layer to achieve over 20%. Thus, we believe that this approach will be an effective design strategy capable of enhancing the performance of PSCs with less hysteresis.
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•Introducing 4-ClBA-TiO2 for high performance PSCs..•Modified TiO2 with 4-ClBA enhanced the grain size and crystalline nature of the perovskite film.•Thereby affords a PCE over 20% in PSCs with negligible hysteresis.
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