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The synthesis and characterization of two D–A–D–A–D push–pull organic semiconductors based on either bis- (2-ethylhexyloxy) benzo [1,2- b :4,5- b ′] dithiophene or bis- (triisopropylsilylethynyl) benzodithiophene electron rich core are described. The optical and electrochemical properties of these compounds indicate that these materials can absorb sunlight over a wide spectral range from 350 to 700 nm and exhibit suitable energy levels for efficient exciton dissociation. These small molecules were used as donor coupled with phenyl-C 71 -butyric acid methyl ester acceptor for the fabrication of solution processed small molecule bulk heterojunction solar cells. The rigid and -conjugation of the silylacetylene substituted analog π-extended compared to the hexyloxy substituted analog facilitates intermolecular packing interactions of small π–π charge transfer and intermolecular molecule which induce a deep HOMO level, producing a high open circuit voltage of ∼0.98 V. The achieved PCE was 5.69% when the active layer hexyloxy analog: phenyl-C 71 -butyric acid methyl ester was processed with optimized 1-chloronaphathalene additive.

Well-organized (CH3NH3)PbI3 perovskite films fabricated from various solution-processing conditions were characterized and used in hybrid solar cells with PC71BM planar heterojuncion films, exhibiting a high power-conversion efficiency of 12.2% with the better photocurrent and fill factor compared to those with PC61BM due to a better spectral response in the visible region and a better planar junction with the Ag electrode than the PC61BM.

High-performance organic semiconductors based on an electron-rich alkylsilylethynyl benzodithiophene (TIPSBDT) core were newly synthesized and characterized for use in solution-processed small-molecule organic solar cells. The rigid and extended π-conjugation of the TIPSBDT motifs facilitates intramolecular charge transfer and intermolecular π–π packing interactions of semiconducting small molecules in the BHJ film enhanced by processing additives and induces deep HOMO levels producing high open-circuit voltage of ∼1.0 V, exhibiting notable power conversion efficiency of 5.84% from a bulk-heterojunction film with PC61BM.

Two symmetrical planar star-shaped organic small molecules, i.e., DMM-TPA[DTS(FBTTh3)3] (1) and TPA[DTS(FBTTh3)3] (2), with fused TPA and TPA core donors, respectively, and three branched DTS(FBTTh3) units were synthesized and characterized. These small molecules were used donor materials along with a PC71BM acceptor for solution-processed bulk heterojunction solar cells. The power conversion efficiency (PCE) of the solar cells based on 1 and 2 is about 2.87% and 2.51%, respectively, when the active layers were processed from a CB solvent. The higher PCE of the solar cell based on 1 may be attributed to its low bandgap and broad absorption profile as compared to 2. The PCE of the solution-processed SMBHJ solar cells was improved up to 5.16% and 4.70% for 1 and 2, respectively, when the active layers were processed with 4 v% DIO as an additive in the CB solvent. The enhancement in the PCE was mainly due to the increase in Jsc and FF, which is attributed to the balanced charge transport between the electron and hole transport and reduction in the bimolecular recombination, leading to an increase in the PCE.

Dye sensitized solar cells performances using two organic dyes with fluorinated-benzothiadiazole spacer, 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9 H -fluoren-2-yl)-amino]-5-fluoro-phenyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid ( JK-311 ) and 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9 H -fluoren-2-yl)-amino]-5,6-difluorophe-nyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid ( JK-312 ), were systematically investigated by solar simulation equipment, stepped light-induced transient measurements of photocurrent and voltage, and electrochemical impedance spectroscopy. To investigate substituent effect of fluorine atom on benzothiadiazole, molecular orbital calculations of two dyes using a time dependent density functional theory model with B3LYP/3-31G* were also carried out. JK-312 showed a unique electronic transition from HOMO-1 to LUMO. Short circuit current and open-circuit voltage in DSSCs performances were increased by the introduction of fluorine atom into spacer segment, compared to fluorine-free dyes.

We meticulously designed organic antenna for the ruthenium phthalocyanine. A significant enhance-ment of photocurrent in JK-107 is attributed to a Forster energy transfer and intramolecular electro...

The symmetrical planar star-shaped organic semiconductor DMM-TPA-[DTS(BTTh(3))](3) with fused TPA core donor and three branch motifs, DTS(BTTh(3)), exhibited efficient p-type semiconducting performance in solution-processed SMOSCs and OFETs compared to the tilted star-shaped TPA-[DTS(BTTh(3))](3); a noteworthy PCE value of 4.16% was observed, with a hole mobility and on/off ratio of 7.6 × 10(-3) cm(2) V(-1) s(-1) and 5 × 10(6), respectively.

In this study, 1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole-based metal-free organic dyes containing three different non planar electron donor groups such as methoxy or hexyloxy substituted triphenylamine and difluorenephenylamine were prepared in order to see the effect of electron donor groups on the opto-electrical properties and applied in dye-sensitized solar cells (DSSC). All three dyes showed broad absorption band in visible part of the solar spectrum (∼300 nm–600 nm). The dye ( TPTDYE-3 ) containing sterically less hindered methoxy substituted triphenylamine was found to show relatively red shifted absorption compared to that of the dye ( TPTDYE-4 ) containing hexyloxy substituted triphenylamine or the dye ( TPTDYE-5 ) containing difluorenephenylamine. The optical band gaps of the three dyes were calculated to be 2.19 eV, 2.22 eV and 2.24 eV, respectively, and the highest occupied molecular orbital (HOMO) energy levels of the three dyes were found to be located at 0.65 V, 0.68 V and 0.75 V, respectively. The DSSC performance of each dye was investigated with and without coadsorbent. The maximum solar to electrical energy conversion efficiencies ( η ) of the DSSCs made from only sensitizer were 4.18%, 5.28% and 5.42% while those of the DSSCs made from sensitizer with coadsorbent were 5.47%, 5.58% and 5.63%, respectively.

The synthesis and photovoltaic characteristics of new organic semiconductors, [bisDMFA-Th]-BT-HxTh3 (1), [bisDMFA-Th]-MonoF-BT-HxTh3 (2), and [bisDMFA-Th]-DiF-BT-HxTh3 (3), are reported. These semiconductors have an unsymmetrical donor A–acceptor–donor B (DA-A-DB) framework composed of a benzothiadiazole (BT; fluorinated or unfluorinated) acceptor between two different donors, bisDMFA and terthiophene. We have demonstrated that these compounds are suitable for use in p-type organic semiconductors for high efficiency solution-processed small molecule organic solar cells (SMOSCs), for which we achieved a remarkable power conversion efficiency of 4.24% with a maximum Voc of 0.89 V. The fluorine substitution on BT decreased its HOMO level and increased hole mobilities of [bisDMFA-Th]-BT-HxTh3 derivatives, leading to an increased Voc in the SMOSCs and improved hole carrier transport properties of the material. In addition, we determined that the insertion of a TiOx functional layer into a bulk heterojunction (...

Five functionalized organic dyes (H6-10) containing a phenanthroimidazole unit as an electron donor were synthesized and characterized for use in dye-sensitized solar cell (DSSC) applications. Under standard global AM 1.5 solar conditions, the DSSCs based on dye H6 displayed the best performance, with an incident photon-to-current conversion efficiency (IPCE) exceeding 70% at wavelengths of 400–530 nm, a short-circuit photocurrent density of 10.98 mA cm −2 , an open-circuit voltage of 0.68 V, a fill factor of 0.69, and an overall conversion efficiency of 5.12%. This efficiency is ∼94% of that for JK2 cells (5.46%) and ∼72% of that for N719 cells (7.07%) under the same conditions.

Two new triphenylamine-based metal-free organic dyes ( TPTDYE-1 and TPTDYE-2 ) containing 1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole as a new π-conjugated chromophore were synthesized for dye-sensitized solar cell (DSSC) applications. TPTDYE-1 containing three donor groups around the acceptor group was found to show relatively narrow absorption band from 300 nm to 470 nm while TPTDYE-2 having extended π–π delocalization between the donor and acceptor group showed broad absorption band from 300 nm to 550 nm. The electrochemical studies indicate that the HOMO–LUMO energy gap of TPTDYE-1 is considerably wider than that of TPTDYE-2 . The dye-sensitized solar cell performance of each dye was investigated, and the TPTDYE-2 -sensitized cell was found to show a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 75%, a short-circuit photocurrent density ( J sc ) of 13.50 mA/cm 2 , an open-circuit voltage ( V oc ) of 0.72 V, and a fill factor (FF) of 0.69, corresponding to an overall conversion efficiency of 6.71% under simulated AM 1.5 irradiation (100 mW/cm 2 ). Under the same condition the TPTDYE-1 -sensitized cell showed the same IPCE value of 75% with a promising conversion efficiency of 6.00%, a J sc of 11.11 mA/cm 2 , a V oc of 0.76 V, and a FF of 0.71.

New efficient push-pull organic semiconductors comprising of on the N , N -(6-bis(9,9-dimethyl-9 H -fluoren-2-yl)amino-benzo[ b ]thiophen (bisDMFABT) donor and the various acceptors such as NO 2 , DCBP, and TCF, which were linked with thiophene or vinyl thiophene π-conjugation bridges, were synthesized, and their photovoltaic characteristics were investigated in solution processed small molecule organic solar cells (SMOSCs). The intramolecular charge transfers of these materials were effectively appeared in between bisDMFABT donor and acceptors, depending on the electron-withdrawing strength of acceptors. The organic semiconductor having DCBF acceptor exhibited the best power conversion efficiency of 3.22% with short circuit current of 9.64 mA/cm 2 , fill fator of 0.42, and open circuit voltage of 0.80 V in SMOSC devices with TiO x thin layer.

New unsymmetrical low band-gap push–pull squaraine chromophores, [TPA-bisHT-HP]-X-Ind [X: SQ, diCNSQ], which are composed of triphenylamine electron donating, π-conjugated dithiophene-pyrrole bridging, and squaraine-indol electron withdrawing moieties, for their application in solution processed BHJ solar cell. The [TPA-bisHT-HP]-diCNSQ-Ind having the stronger electron withdrawing moiety exhibits significantly the red-shifted absorption spectrum due to its strong intramolecular charge transfer in solution as well as in solid-state. The bulk-heterojunction photovoltaic devices fabricated with [TPA-bisHT-HP]-diCNSQ-Ind/C71-PCBM film exhibited a PCE of 2.05% (±0.07) with short-circuit current (Jsc)=9.05 mA/cm2, fill factor (FF)=0.33, and open-circuit voltage (Voc)=0.69 V, which is ∼3 times higher efficiency compared to [TPA-bisHT-HP]-SQ-Ind/C71-PCBM BHJ films.

New symmetrical low band-gap small molecule materials, SQ-bis[HP-HT2-TPA] and SQ-bis[HP-HT2-BT] incorporating as novel derivative of squaraine-pyrrole framework and π-extended thiophene with triphenyamine (TPA) and benzothiophene (BT) end group, have been synthesized and characterized. The effects of TPA moiety were investigated. Compared to SQ-bis[HP-HT2-BT], SQ-bis[HP-HT2-TPA] exhibited three times improved transporting property of hole carrier and four times enhanced absorptivity by more efficient intermolecular π−π interaction for high-efficiency bulk heterojunction (BHJ) device, suggesting that TPA contributes to a better hole mobility. The bulk-heterojunction photovoltaic devices fabricated with SQ-bis[HP-HT2-TPA]/C71-PCBM BHJ film had an average power-conversion efficiency of 1.83%(±0.12) under 100 mW/cm2, with a short-circuit current (Jsc) of 9.32 mA/cm2, fill factor (FF) of 0.30, and open-circuit voltage (Voc) of 0.65 V, which has ∼42% higher efficiency compared to SQ-bis[HP-HT2-BT]/C71-PCBM BHJ films.

M-CNTs (Multiwall Carbon Nano Tubes) can be used as an electrode, transferring electrons and heat very easily. This property helps transfer electrons created in TiO2 layer of DSSC (Dye-sensitized Solar Cell). CNTs layer with TiO2 utilized for the photocatalyst is expected to contribute to improve the efficiency of the solar cell. The Photocatalyst of TiO2 thin film was manufactured from titanium isopropoxide, ethanol, and HCl by a sol-gel process. To determine the property of TiO2 thin film with CNT, we performed to mix acid dispersed CNT in TiO2 Sol-gel and make coating membranes using sol-gel with different densities of CNT. It was found that the crystal structure changed from the anatase phase to the rutile phase having higher efficiency by XRD measure after treatment of high temperature sintering. To demonstrate the property of each sample, the transmittance of the TiO2 thin film was measured by a spectrometer and dispersion of CNT of the thin film was measured by SEM. In conclusion, the capacitance as the parameter which can affect performance of DSSC was investigated.

Three organic sensitizers JK-87, JK-88, and JK-89 containing a bulky spirobifluorene unit in the bridged group are designed and synthesized. Under standard global A.M. 1.5 solar condition, the JK-89 sensitized cell gave a short-circuit photocurrent density (Jsc) of 13.02 mA cm−2, an open-circuit voltage (Voc) of 0.75 V, and a fill factor of 0.70, corresponding to an overall conversion efficiency η of 6.83%. The η of JK-89 is higher than those of other two cells due to the larger Jsc. The improved Jsc value is mainly attributed to the broad and red-shifted absorption band.

A facile new protocol for the synthesis of iodinated derivatives of fluorinated benzothiadiazoles is demonstrated for the production of p-type semiconducting materials. The newly synthesized small-molecule compounds bis[TPA-diTh]-MonoF-BT and bis[TPA-diTh]-DiF-BT exhibited a power conversion efficiency of 2.95 % and a high open-circuit voltage of 0.85 V in solution-processed small-molecule organic solar cells.

New electron-rich anthracene derivatives containing triarylamine hole stabilizers, 2,6-bis[5,5'-bis(N,N'-diphenylaniline)-2,2'-bithiophen-5-yl]-9,10-bis-[(triisopropylsilyl)ethynyl]anthracene (TIPSAntBT-TPA) and 2,6-bis(5,5'-bis{4-[bis(9,9-dimethyl-9H-fluoren-2-yl)amino]phenyl}-2,2'-bithiophen-5-yl)-9,10-bis-[(triisopropylsilyl)ethynyl]anthracene (TIPSAntBT-bisDMFA), linked with π-conjugated bithiophene bridges, were synthesized and their photovoltaic characteristics were investigated in solution-processed small-molecule organic solar cells (SMOSCs). These new materials exhibited superior intramolecular charge transfer from triarylamine to anthracene, leading to a more electron-rich anthracene core that facilitated electron transfer into phenyl-C(61)-butyric acid methyl ester. Compared with TIPSAntBT and triarylamine, these materials show a threefold improvement in hole-transporting properties and better photovoltaic performance in solution-processed SMOSCs, with the best power conversion efficiency being 2.96 % at a high open-circuit voltage of 0.85 V.

A new type of organic sensitizers incorporating a planar amine unit have been synthesized and demonstrated to be a highly efficient sensitizers, showing evidence of lateral interactions on the TiO(2) surface. Under standard global air mass 1.5 solar conditions, the JK-98 sensitized cell gave a short circuit photocurrent density (J(sc)) of 16.78 mA cm(-2), an open-circuit voltage (V(oc)) of 0.745 V, and a fill factor (ff) of 0.70, corresponding to an overall conversion efficiency (η) of 8.71%.

We have synthesized and characterized four organic dyes (H1-H4) based on a 3,6-disubstituted carbazole donor as sensitizers in dye-sensitized solar cells. These dyes have high molar extinction coefficients and energy levels suitable for electron transfer from an electrolyte to nanocrystalline TiO(2) particles. Under standard air mass 1.5 global (AM 1.5 G) solar irradiation, a device using dye H4 exhibits a short-circuit current density (J(sc)) of 13.7 mA cm(-2), an open-circuit voltage (V(oc)) of 0.68 V, a fill factor (FF) of 0.70, and a calculated efficiency of 6.52%. This performance is comparable to that of a reference cell based on N719 (7.30%) under the same conditions. After 1000 hours of visible-light soaking at 60 °C, the overall efficiency remained at 95% of the initial value.

A new series of stable, unsymmetrical squaraine near-IR sensitizers (JK-216 and JK-217), which are assembled using both thiophenyl pyrrolyl and indolium groups, exhibit a panchromatic light harvesting up to 780 nm. The JK-216 based cell exhibited a record efficiency of 6.29% for near-IR DSSCs. In addition, the JK-217 device showed an excellent stability under a light soaking test at 60 °C for 1000 h.

Annulated thiophene perylene bisimides and their triphenyl-amine based oligomers have been synthesized. One of the oligomers FPTTPA has been demonstrated to be an efficient electron donor in bulk heterojunction (BHJ) organic solar cells, giving a power conversion efficiency of 1.42%.

A new series of stable, unsymmetrical squaraine near-IR sensitizers (JK-216 and JK-217), which are assembled using both thiophenyl pyrrolyl and indolium groups, exhibit a panchromatic light harvesting up to 780 nm. The JK-216 based cell exhibited a record efficiency of 6.29% for near-IR DSSCs. In addition, the JK-217 device showed an excellent stability under a light soaking test at 60 degrees C for 1000 h.

An organic dye (JK218) with thiol moiety as an anchoring group was synthesized and explored to assemble a cosensitized TiO2 electrode in combination with an inorganic CdS quantum-dot. Due to the selective adsorption of JK218 on the surface of CdS through thiol group, the developed cosensitized electrode demonstrates cascade architecture with CdS coating on TiO2 while JK218 functions as a covering on CdS. Most importantly, the energy levels of the TiO2–CdS-JK218 electrode were also found to be stepwise aligned, which accordingly makes electrons efficiently inject from JK218 to CdS under illumination and finally collect to TiO2. This constructed cosensitized electrode with an organic sensitizer (JK218) and an inorganic quantum-dot (CdS) being selectively bonded together is expected to be valuable for the interface design of next generation solar cells.