Molecularly engineered novel dopant‐free hole‐transporting materials for perovskite solar cells (PSCs) combined with mixed‐perovskite (FAPbI3)0.85(MAPbBr3)0.15 (MA: CH3NH3+, FA: NH=CHNH3+) that exhibit an excellent power conversion efficiency of 18.9% under AM 1.5 conditions are investigated. The mobilities of FA‐CN, and TPA‐CN are determined to be 1.2 × 10−4 cm2 V−1 s−1 and 1.1 × 10−4 cm2 V−1 s−1, respectively. Exceptional stability up to 500 h is measured with the PSC based on FA‐CN. Additionally, it is found that the maximum power output collected after 1300 h remained 65% of its initial value. This opens up new avenue for efficient and stable PSCs exploring new materials as alternatives to Spiro‐OMeTAD.

Two novel star-shaped hole transporting materials (HTMs). i.e. [BMPA-EDOT](3)-TPA and [BMPA-BTD](3)-TPA with EDOT or BTD moiety as side arm have been designed and synthesized. The optical and electronic properties of these HTMs were modified by changing the side arms. Surprisingly, the cell performance was dependent on the moietys such as EDOT or BTD of side arms. Perovskite solar cells with [BMPAEDOT](3)-TPA gave a short circuit photocurrent density (J(sc)) of 21.01 mA cm(-2), an open circuit voltage (V-oc) of 0.916 V, and a fill factor (ff) of 0.67, corresponding to an overall conversion efficiency of 12.92%. (C) 2015 Elsevier Ltd. All rights reserved.

New star-shaped hole transport materials including a 1,3,5-triazine core have been successfully synthesized and investigated for high performance perovskite solar cells.

The optimized devices after TSA treatment showed PCEs of 7.04% and 6.16% when employing DIN-IND : PC71BM (1 : 2) and DIN-CN : PC71BM (1 : 2), respectively.

We demonstrate for the first time an asymmetric squaraine-based low band-gap hole transporting material, which acted as both light harvesting and hole transporting layers in methylammonium lead triiodide perovskite solar cells. Opto-electrochemical characterization revealed extremely high molar extinction coefficients of the absorption bands in the low energy region and prominent space charge delocalization due to its electronically asymmetric nature. A suitable band alignment of the squaraine HOMO level with the valence band edge of the perovskite, and the conduction band of the TiO2 with LUMO of the perovskite allowed a cascade of hole extraction and electron injection, respectively. Red-shifted absorption was observed for both HTMs in thin films coated on the perovskite, and the optimized devices exhibited an impressive PCE of 14.7% under full sunlight illumination (100 mW cm(-2), AM1.5 G). The efficiency value is comparable to that of the devices using a state-of-the-art spiro-OMeTAD hole transport layer under similar conditions. Ambient stability after 300 h revealed that 88% of the initial efficiency remained for , and almost no change for , indicating that the devices had good long-term stability thus suggesting that the asymmetric squaraines have great potential as a dual-functional HTM for high performance perovskite solar cells.

Synthesis and characterization of novel acceptor–donor–acceptor small molecules with different end group acceptors such as dicyanovinyl, cyanoacetate and indenedione, denoted as SM1, SM2 and SM3, respectively, linked with same central S, N-heteropentacene donor is described. These small molecules are used as electron donor along with the PC71BM as an electron acceptor for the fabrication of solution processed bulk heterojunction organic solar cells. The optimized devices based on as cast SM1:PC71BM, SM2:PC71BM and SM2:PC71BM showed power conversion efficiency about 2.01%, 1.60% and 2.65%, respectively and improved to 5.64%, 4.24% and 6.64%, respectively, using active layer processed with two steps annealing, i.e. combination of thermal annealing and subsequent solvent vapor annealing. This increase in the power conversion efficiency was due to the enhancement in Jsc and FF attributed to the enhancement of the light harvesting ability of the active layer, which is reflected by favorable nanoscale morphology.

Two D-A-D-A-D small molecules based on same 5,10-dihydroindolo [3,2-b]indole central donor core and different benzothiadiazole (BT) and fluorine substituted BT (FBT) acceptor units, denoted as p-DINI-(BTTh3)2 (1) and p-DINI-(FBTTTh3)2 (2), respectively were synthesized and their optical and electrochemical properties were investigated. These molecules were applied as donor along with PC71BM as electron acceptor for the fabrication of solution processed bulk heterojunction organic solar cells. The solar cells prepared from the optimized active blended layer (1:2) cast from dichlorobenzene (DCB) showed overall power conversion efficiency (PCE) of 2.02% and 2.70% for 1 and 2, respectively as donor. The higher PCE of 2 as compared to 1 is attributed to the higher hole mobility and broader IPCE spectra. In order to improve the PCE we have employed a two step treatment of active layer i.e. solvent vapor annealing after thermal annealing (SVA-TA) and the PCE has been enhanced up to 4.14% and 5.27% for optimized 1:PC71BM and 2:PC71BM active layers, respectively. The improvement in the PCE has been resulted from the improvement in the balanced charge transport and better crystallinity of the donor in the blended active layer.

Novel symmetric oligomer hole transporting materials (HTMs) incorporating 3,4-ethylenedioxythiophene (EDOT) and 2,1,3-benzothiadiazole (BTD) cores have been synthesized and tested for high performance perovskite solar cells. A maximum energy conversion efficiency of 14.23% has been achieved by employing with the electron donating EDOT unit as the core, which is comparable to that of the traditional (14.55%).

The synthesis and characterization of two D-A-D-A-D push-pull organic semiconductors based on either his- (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 pi-extended compared to the hexyloxy substituted analog facilitates intermolecular packing interactions of small pi-pi charge transfer and intermolecular molecule which induce a deep HOMO level, producing a high open circuit voltage of similar to 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. (C) 2015 Elsevier Ltd. All rights reserved.

Novel steric bulky hole transporting materials (HTMs) with two or four N,N-di(4-methoxyphenyl)aminophenyl units have been synthesized. When the EtheneTTPA was used as a hole transporting material in perovskite solar cell, the power conversion efficiency afforded 12.77 % under AM 1.5 G illumination, which is comparable to the widely used spiro-OMeTAD based solar cell (13.28 %).

Ternary spinel NiCo2S4 nanorods are tested for the first time as anode electrodes for Li ion batteries. When the electrode is fabricated using the carboxymethyl cellulose-polyacryl amide composite binder, it is found to restrict or suppress the formation of a polymeric gel passivation layer. As a result, the electrode not only delivers excellent specific capacity, but also an outstanding rate and cyclic stability with almost no decay up to 100 charge-discharge cycles.

Nitrogen-doped ordered mesoporous carbons (N-OMCs) with different morphologies are prepared as oxygen reduction reaction (ORR) catalysts through pyrolysis of iron phthalocyanine-infiltrated SBA-15 silica with different mesochannel lengths. Excellent ORR activity with a nearly four-electron transfer process is observed in both alkaline and acidic media. In particular, the difference in half-wave potential for ORR relative to commercial Pt/C catalyst is only 50mV negative in acidic medium, whereas it is 50mV more positive in alkaline medium. Interestingly, it is found that although the use of iron is necessary for the preparation of highly active nitrogen-doped ORR carbon catalysts, its presence is not necessary for N-OMC to be active in the ORR in either alkaline or acidic media. In addition, the ORR activity increases gradually with decreasing mesopore channel length, with maximum activity in N-OMC with short channels, demonstrating the high synergistic influence of structural morphology on ORR in heteroatom-doped carbon.

Three organic sensitizers consisting of carbazole as an electron donor, indeno[1,2-b]thiophene as the bridging unit have been synthesized and characterized for use in dye-sensitized solar cells. Time-dependent density functional theory studies are indicated that large intramolecular charge transfer takes place from the highest occupied molecular orbital to the lowest unoccupied molecular orbital though the donor is twisted (similar to 50 degrees) with respect to the pi-linker. However, the introduction of indeno[1,2-b]thiophene as a planar pi-linker unit is presumed to be the reason for a strong molar absorption coefficient and a red-shifted absorption band. Air mass 1.5 global illumination (100 mW cm(-2)), the 3-(5-(6-(3,6-bis(2,4-bis(hexyloxy)phenyl)-9H-carbazol-9-yl)-4,4-dimethyl-4H-indeno[1,2-b]thiophen-2-yl)thi-oph-2-yl)-2-cyanoacrylic acid based device displayed the best performance: an open-circuit voltage of 826 mV, a short-circuit current density of 9.16 mA cm(-2), a fill factor of 0.777, and an overall conversion efficiency of 5.88%. Upon changing the electrolyte from iodine to cobalt electrolyte, 3-(5-(6-(3,6-bis(2,4-bis(hexyloxy)phenyl)-9H-carbazol-9-yl)-4,4-dimethyl-4H-indeno[1,2-b]thiophen-2-yl)thioph-2-yl)-2-cyanoacrylic acid based dye-sensitized solar cells gave the remarkably improved overall conversion efficiency (6.66%), which is one of the highest values based on carbazole sensitizers. (C) 2015 Elsevier Ltd. All rights reserved.

Novel star-shaped hole transporting materials (HTMs) with a bis-dimethylfluorenylamino moiety have been synthesized and evaluated for high performance perovskite solar cell applications. Maximum power conversion efficiency of 14.21% has been achieved by using the HTM with a fused TPA core and the long-term stability was also shown to be comparable with that of .

In this work, we synthesized novel hole transporting materials (HTMs) and studied their impact on the stability of perovskite-based solar cells (PSCs). The steady-state maximum power output of devices in working condition was monitored to assess the stability and predict the lifetime of PSCs prepared using different HTMs. We showed that the HTM has a significant impact on the device lifetime and found that novel silolothiophene linked methoxy triphenylamines (Si-OMeTPAs) enable more stable PSCs. We reported Si-OMeTPA based devices with a half-life of 6 K h, compared to 1 K h collected for the state-of-the-art PSCs using spirofluorene linked methoxy triphenylamines (spiro-OMeTADs) as HTMs. We demonstrated that such a clear improvement is correlated to the superior thermal stability of silolothiophene compared to the spirofluorene linked triphenylamine HTMs.

Edge-selectively halogenated graphene nanoplatelets (XGnPs, X=Cl, Br, and I) were prepared by the mechanochemically driven reaction between graphite and diatomic halogen molecules (Cl2, Br2 or I2). The contents of halogens (Cl, Br, and I) in XGnPs were 3.18, 1.77, and 0.66at%, respectively, by X-ray photoelectron spectroscopy. The XGnPs as counter electrodes (CEs) showed remarkably enhanced electrocatalytic activities toward Co(bpy)33+ reduction reaction in dye-sensitized solar cells (DSSCs) with an excellent electrochemical stability. Amongst XGnPs, IGnP-CE demonstrated the lowest charge-transfer resistance (Rct) of 0.46Ωcm2 at the CE/electrolyte interface. This value is much lower than that of Pt-CE (0.81Ωcm2). In addition, the DSSC with IGnP-CE had the highest fill factor (71.3%) and cell efficiency (10.31%), whereas those of DSSCs with Pt-CE were only 70.6% and 9.92%, respectively.

A new unsymmetrical low bandgap push–pull squaraine chromophore bis-DMFA-Th-SQ-Th-DCA (JK216D) was synthesized and its optical and electrochemical properties were investigated.

In this report, we demonstrate the superior performance of dye-sensitized solar cells (DSSCs) with novel, metal-free counter electrodes (CEs) comprised of copolymer-templated nitrogen-enriched nanocarbons (CTNCs) with well-controlled morphology, nanoporosity, and nitrogen content. This superior performance is due to the high catalytic activity of CTNCs toward the reduction of Co(bpy)(3)(2+/3+), as evidenced by unusually low charge transfer resistance (R-CT) at the CE-electrolyte interface. The observed activity is attributed to the combination of the high surface area of CTNCs afforded by a three-dimensional, hierarchical pore structure, and to their unique electronic properties stemming from the presence of nitrogen heteroatoms located on the edges of nanographitic domains. Altogether, the use of CTNC CEs enhanced the efficiency and fill factor (FF) of JK-306 dye, Co(bpy)(3)(2+/3+) redox couple based DSSCs at one sun illumination up to 10.32% and 73.5%, respectively, suggesting the considerable promise of these materials as an attractive alternative to costly Pt-based CEs. Interestingly, the use of CTNCs did not lead to the analogous beneficial lowering of R-CT in I-/I-3(-) redox couple based N719-sensitized DSSCs, limiting their FF and short circuit current density (J(SC)). This chemical specificity indicates that the type of nitrogen bonding configurations, rather than the total N-content, is the key factor determining the catalytic activity.

SN(BTTh2)2 and SN(BTAOTh2)2, containing an electron rich planar S,N-heteropentacene flanked with alkoxy substituted and unsubstituted benzothiadiazole and end capped with hexyl-substituted bi-thiophene units, were designed and synthesized.

Efficient hole-transporting materials (HTMs), TAZ-[MeOTPA]2 and TAZ-[MeOTPATh]2 incorporating two electron-rich diphenylamino side arms, through direct linkage or thiophen bridges, respectively, on the C3- and C5-positions of a 4-phenyl-1,2,4-triazole core were synthesized. These synthetic HTMs with donor-acceptor type molecular structures exhibited effective intramolecular charge transfer for improving the hole-transporting properties. The structural modification of HTMs by thiophene bridging might increase intermolecular π-π stacking in the solid state and afford a better spectral response because of their increased π-conjugation length. Perovskite-based cells using TAZ-[MeOTPA]2 and TAZ-[MeOTPATh]2 as HTMs afforded high power conversion efficiencies of 10.9 % and 14.4 %, respectively, showing a photovoltaic performance comparable to that obtained using spiro-OMeTAD. These synthetically simple and inexpensive HTMs hold promise for replacing the more expensive spiro-OMeTAD in high-efficiency perovskite solar cells.