High‐Performance Platinum‐Free Dye‐Sensitized Solar Cells with Molybdenum Disulfide Films as Counter Electrodes

By using a radio‐frequency sputtering method, we synthesized large‐area, uniform, and transparent molybdenum disulfide film electrodes (1, 3, 5, and 7 min) on transparent and conducting fluorine‐doped tin oxide (FTO), as ecofriendly, cost‐effective counter electrodes (CE) for dye‐sensitized solar cells (DSSCs). These CEs were used in place of the routinely used expensive platinum CEs for the catalytic reduction of a triiodide electrolyte. The structure and morphology of the MoS₂ was analyzed by using Raman spectroscopy, X‐ray diffraction, and X‐ray photoemission spectroscopy measurements and the DSSC characteristics were investigated. An unbroken film of MoS₂ was identified on the FTO crystallites from field‐emission scanning electron microscopy. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel curve measurements reveal the promise of MoS₂ as a CE with a low charge‐transfer resistance, high electrocatalytic activity, and fast reaction kinetics for the reduction of triiodide to iodide. Finally, an optimized transparent MoS₂ CE, obtained after 5 min synthesis time, showed a high power‐conversion efficiency of 6.0 %, which comparable to the performance obtained with a Pt CE (6.6 %) when used in TiO₂‐based DSCCs, thus signifying the importance of sputtering time on DSSC performance.     

Enhanced Performance of Organic/Inorganic Hybrid Nanomaterials bearing Impregnated [PdL2] Complexes as Counter‐Electrode Catalyst for Dye‐Sensitized Solar Cells

N‐coordinate Pd²⁺ complexes [PdL₂] (L: N‐N‐quinoline‐8‐yl‐R‐benzenesulfonamides) ( 6–10 ) and [PdL₂] complexes assembled on multi‐wall carbon nanotubes (MWCNTs) hybrid nanomaterials were fabricated and characterized by various techniques. The [PdL₂] impregnated MWCNTs materials ( 11–15 ) were applied as a counter electrode (CE) catalyst for triiodide to iodide reduction reaction in the dye‐sensitized solar cells (DSSC) and investigated electro‐catalytic activities. The MWCNTs‐supported [PdL₂] CEs ( 11–15 ) are exhibits as Pt‐free CE with good power conversion efficiencies (PCEs), and compared to platinum and bare MWCNTs CEs and the PCE of bare MWCNTs was clearly improved by means of [PdL₂] complexes ( 6–10 ). The DSSCs based on the hybrid counter electrodes (CEs) ( 11–15 ) and bare MWCNTs are indicated a relative efficiency ( ? _rel ) of 64.27%, 54.07%, 53.75%, 51.52% 44.82% and 27.27% concerning a Pt CE control device set at 100%. The report emphasizes that [PdL₂] impregnated MWCNTs type counter electrodes (CEs) ( 11–15 ) are promising as effectively catalyst in working device design, particularly taking into account the eco‐friendly approach of the hybrids.     

Platinum‐Free Binary Co‐Ni Alloy Counter Electrodes for Efficient Dye‐Sensitized Solar Cells

Dye‐sensitized solar cells (DSSCs) have attracted growing interest because of their application in renewable energy technologies in developing modern low‐carbon economies. However, the commercial application of DSSCs has been hindered by the high expenses of platinum (Pt) counter electrodes (CEs). Here we use Pt‐free binary Co‐Ni alloys synthesized by a mild hydrothermal strategy as CE materials in efficient DSSCs. As a result of the rapid charge transfer, good electrical conduction, and reasonable electrocatalysis, the power conversion efficiencies of Co‐Ni‐based DSSCs are higher than those of Pt‐only CEs, and the fabrication expense is markedly reduced. The DSSCs based on a CoNi_0.25 alloy CE displays an impressive power conversion efficiency of 8.39 %, fast start‐up, multiple start/stop cycling, and good stability under extended irradiation.     

Podlike N‐Doped Carbon Nanotubes Encapsulating FeNi Alloy Nanoparticles: High‐Performance Counter Electrode Materials for Dye‐Sensitized Solar Cells

Podlike nitrogen‐doped carbon nanotubes encapsulating FeNi alloy nanoparticles (Pod(N)‐FeNi) were prepared by the direct pyrolysis of organometallic precursors. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization measurements revealed their excellent electrocatalytic activities in the I^?/I₃^? redox reaction of dye‐sensitized solar cells (DSSCs). This is suggested to arise from the modification of the surface electronic properties of the carbon by the encapsulated metal alloy nanoparticles (NPs). Sequential scanning with EIS and CV further showed the high electrochemical stability of the Pod(N)‐FeNi composite. DSSCs with Pod(N)‐FeNi as the counter electrode (CE) presented a power conversion efficiency of 8.82 %, which is superior to that of the control device with sputtered Pt as the CE. The Pod(N)‐FeNi composite thus shows promise as an environmentally friendly, low‐cost, and highly efficient CE material for DSSCs.     

Transparent Metal Selenide Alloy Counter Electrodes for High‐Efficiency Bifacial Dye‐Sensitized Solar Cells

The exploration of cost‐effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye‐sensitized solar cells (DSSCs). Transparent counter electrodes based on binary‐alloy metal selenides (M‐Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution‐based method and employed in efficient bifacial DSSCs. Owing to superior charge‐transfer ability for the I^?/I₃^? redox couple, electrocatalytic activity toward I₃^? reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30 % and 4.63 % for Co_0.85Se, 7.85 % and 4.37 % for Ni_0.85Se, 6.43 % and 4.24 % for Cu_0.50Se, 7.64 % and 5.05 % for FeSe, and 9.22 % and 5.90 % for Ru_0.33Se in comparison with 6.18 % and 3.56 % for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels.     

Efficient Counter Electrode Manufactured from Ag2S Nanocrystal Ink for Dye‐Sensitized Solar Cells

It is generally believed that silver or silver‐based compounds are not suitable counter electrode (CE) materials for dye‐sensitized solar cells (DSSCs) due to the corrosion of the I^?/I₃^? redox couple in electrolytes. However, Ag₂S has potential applications in DSSCs for catalyzing I₃^? reduction reactions because of its high carrier concentration and tiny solubility product constant. In the present work, CE manufactured from Ag₂S nanocrystals ink exhibited efficient electrocatalytic activity in the reduction of I₃^? to I^? in DSSCs. The DSSC consisting of Ag₂S CE displayed a higher power conversion efficiency of 8.40 % than that of Pt CE (8.11 %). Moreover, the devices also showed the characteristics of fast activity onset, high multiple start/stop capability and good irradiated stability. The simple composition, easy preparation, stable chemical property, and good catalytic performance make the developed Ag₂S CE as a promising alternative to Pt CE in DSSCs.     

Graphene oxide sheet–polyaniline nanohybrids for enhanced photovoltaic performance of dye‐sensitized solar cells

In this study, photovoltaic (PV) properties of dye‐sensitized solar cells (DSSCs) incorporated with graphene oxide nanosheet‐polyaniline (GOS‐PANI) nanohybrid/poly(ethylene oxide) (PEO) blend gel electrolytes were investigated. Chemical structure and composition of GOS‐PANI nanohybrids were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy. The images of transmission electron microscopy revealed that PANI nanorods were anchored to the single‐layered GOS for the GOS‐PANI nanohybrids. Ionic conductivities of the GOS‐PANI/PEO–based gel electrolytes were measured using a conductivity meter. The electrochemical catalytic activities of the GOS‐PANI nanohybrids were determined through cyclic voltammetry. These GOS‐PANI nanohybrids were served as the extended electron transfer materials and catalyst for the electrochemical reduction of I₃^?. Due to the enhancement of the ionic conductivity and electrochemical catalytic activity of the gel electrolyte, better PV performance was observed for the DSSCs based on the GOS‐PANI containing electrolytes as compared to the pristine PEO electrolyte‐based DSSC sample. Moreover, PV performances of the GOS‐PANI/PEO–based DSSCs were closely related to the PANI content of GOS‐PANI nanohybrids. The highest photo‐energy conversion efficiency (5.63%) was obtained for an optimized GOS‐PANI/PEO (5:95, w/w) blend gel electrolyte‐based DSSC sample. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 321–332     

An Interconnected Ternary MIn2S4 (M=Fe,Co, Ni) Thiospinel Nanosheet Array: A Type of Efficient Platinum‐Free Counter Electrode for Dye‐Sensitized Solar Cells

The ternary iron‐group thiospinels of metal diindium sulfides (MIn₂S₄, M=Fe, Co, Ni) with a vertically aligned nanosheet array structure are fabricated through an in situ solvothermal method on F‐doped tin oxide (FTO) substrates, which are employed as one type of platinum (Pt)‐free counter electrodes (CEs) in structure‐dependent dye‐sensitized solar cells (DSSCs). A DSSC assembled with ternary CoIn₂S₄ CE achieves an photoelectric conversion efficiency (PCE) of 8.83 %, outperforming than that of FeIn₂S₄ (7.18 %) and NiIn₂S₄ (8.27 %) CEs under full sunlight illumination (100 mW cm⁻², AM 1.5 G), which is also comparable with that of the Pt CE (8.19 %). Putting aside that the interconnected nanosheet array provides fast electron transfer and electrolyte diffusion channels, the highest PCE of CoIn₂S₄ based DSSC results from its largest specific surface area (144.07 m² g⁻¹), providing abundant active sites and the largest electron injection efficiency from CE to electrolyte.     

Scrutinizing Defects and Defect Density of Selenium‐Doped Graphene for High‐Efficiency Triiodide Reduction in Dye‐Sensitized Solar Cells

Understanding the impact of the defects/defect density of electrocatalysts on the activity in the triiodide (I₃^?) reduction reaction of dye‐sensitized solar cells (DSSCs) is indispensable for the design and construction of high‐efficiency counter electrodes (CEs). Active‐site‐enriched selenium‐doped graphene (SeG) was crafted by ball‐milling followed by high‐temperature annealing to yield abundant edge sites and fully activated basal planes. The density of defects within SeG can be tuned by adjusting the annealing temperature. The sample synthesized at an annealing temperature of 900 °C exhibited a superior response to the I₃^? reduction with a high conversion efficiency of 8.42 %, outperforming the Pt reference (7.88 %). Improved stability is also observed. DFT calculations showed the high catalytic activity of SeG over pure graphene is a result of the reduced ionization energy owing to incorporation of Se species, facilitating electron transfer at the electrode–electrolyte interface.     

Bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) Complex for Efficient Organic Heterojunction Solar Cells

Organic photovoltaic (OPV) cells using metal(II) (Pt, Pd, Cu, and Ni) chelates of 8‐hydroxyquinoline (Hq) or 5,7‐dimethyl‐8‐hydroxy‐quinoline (HMe₂q) as an electron donor were fabricated by vacuum deposition. The bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) [Pt(Me₂q)₂]‐based OPVs showed the best performance with an open voltage (V_OC) of 0.42 V, a short circuit current density (J_SC) of 14.8 mA cm^?2, and a maximum power conversion efficiency (η_P) of 2.4 %. The X‐ray single‐crystal structures together with the grazing incidence X‐ray diffraction (GIXRD) data of thin film samples reveal that the peripheral methyl substituent(s) and platinum(II) ion are essential for the high degree of film crystallinity resulting in improved performance of the as‐fabricated field‐effect transistors (FETs) and OPV cells.     

聚合溶液pH值对染料敏化太阳电池中聚吡咯对电极结构和性能的影响

电化学合成聚吡咯（PPy）时,聚合电解液的pH 值对PPy 薄膜的形貌和性质有较大的影响,进而影响PPy薄膜对I^-/I₃^-的电催化活性以及基于PPy对电极（CE）的染料敏化太阳电池（DSSCs）的光电转换性能. 本文采用电化学恒电位方法,在掺杂氟的SnO₂（FTO）导电玻璃上合成出了对甲苯磺酸根离子掺杂的聚吡咯（PPy-TsO）电极,并将其作为DSSCs 的对电极. 通过改变吡咯聚合时聚合电解液的pH值,借助扫描电镜（SEM）、紫外-可见（UV-Vis）吸收光谱、X-射线光电子能谱（XPS）和循环伏安（CV）等表征技术,详细探讨了聚合溶液pH值对PPy CE形貌、结构及其对I^-/I₃^-的电催化性能的影响. 研究发现在pH 2.0下合成的聚吡咯对阴离子掺杂率最高且链共轭性最佳,具有对I^-/I₃^-氧化还原介质最强的催化能力,基于此PPy CE的电池光电转化效率也最高.pH 值太大或太小都不利于生成具有高掺杂率和高催化活性的PPy电极,组装成DSSCs后的光电转换效率也较低.     

[Pt(topy)(Htopy)(ONO2)] complex (Htopy = 2‐p‐tolylpyridine) and its analogs: 195Pt NMR spectra and fabrication of light‐emitting devices

We report fast, high‐yield syntheses of a series of [Pt(C^∧N)(HC^∧N)X] complexes, where HC^∧N is 2‐phenylpyridine (Hppy) or 2‐p‐tolylpyridine (Htopy) and X^? is Cl^?, Br^?, I^?, ONO₂^?, NO₂^? or SCN^?. The structure of [Pt(topy)(Htopy)(ONO₂)] was analyzed by single‐crystal X‐ray diffraction. Substitution of Cl^? with Br^? or I^? in our complexes shifted the ¹⁹⁵Pt NMR peaks upfield in the order Cl^? < Br^? < I^?, but the magnitudes of their shifts were one‐tenth those observed for non‐cyclometalated platinum(II) complexes. As the two nitrato complexes showed strong emissions in acetonitrile solution—three to six times those of other complexes—they were used to fabricate OLEDs. Although their emissions were not particularly strong, devices fabricated with platinum(II) complexes containing bulky ligands emitted green light with a short lifetime (τ). Copyright © 2009 John Wiley & Sons, Ltd.     

Copper doped manganese dioxide as counter electrode for dye-sensitized solar cells

Many materials have been tried as the counter electrode (CE) material as a substitute to the noble metal Pt in dye-sensitized solar cells (DSSCs). The CE property is critical to the operation of a DSSC as it catalyzes the reduction of I₃^- ions and retrieves the electrons from the photoanode. Here we have explored the application of manganese dioxide (MnO₂) and copper-doped manganese dioxide (Cu-MnO₂) nanoparticles as CE candidates for DSSCs mainly as low-cost alternatives to Pt. A simple hydrothermal method was followed to synthesize α-MnO2 and Cu-MnO2 nanoparticles at a temperature of 140 °C for 14 h. The nanoparticles were characterized to prove its electrocatalytic abilities for DSSCs. DSSC devices fabricated with 10 wt% Cu-MnO₂ as CE showed the best V_OC of 781 mV, I_SC of 3.69 mA/cm², FF of 0.50, and %PCE of 1.7 whereas Pt as CE showed V_OC of 780 mV, I_SC of 14.8 mA/cm², FF of 0.43, and %PCE of 5.83 under 0.85 Sun. The low-cost feature of using Cu-MnO₂ is encouraging to further study the factors that can improve the efficiency of DSSCs with alternative CEs to conventional Pt electrodes.     

Fe/Cu修饰氮掺杂碳纳米管的构筑及催化性能

通过简单的原位化学合成法结合离子交换法制备了Cu修饰氮掺杂碳（Cu-N-C）和Fe/Cu修饰氮掺杂碳纳米管（Fe/Cu-N-C/CNT）,并系统评估了2种催化剂作为染料敏化太阳能电池（dye-sensitized solar cells,DSSCs）对电极在I₃^-/I^-体系中的电化学特性和光伏性能。采用X射线衍射（XRD）、拉曼（Raman）、X射线光电子能谱（XPS）和场发射扫描电镜（FESEM）对合成的催化剂进行组分和形貌表征。结果表明：纳米管状的Fe/Cu-N-C/CNT的石墨化程度比纳米颗粒状的Cu-N-C更高,更有利于I₃^-还原反应中电荷的传输。光伏性能测试结果表明：基于Fe/Cu-N-C/CNT对电极的DSSCs的光电能量转换效率（power conversion efficiency,PCE）达到7.55%,高于相同测试条件下Cu-N-C（6.99%）和Pt（6.76%）对电极的PCE。50圈连续循环伏安测试结果表明：Fe/Cu-N-C/CNT催化剂具有比Cu-N-C更好的电化学稳定性。     

A study of novel macrocyclic copper complex/graphene‐based composite materials for counter electrodes of dye‐sensitized solar cells

In this study, a newly synthesized macrocyclic copper complex, [Cu(C₁₀H₂₀N₈)(C₄H₈N₄)](BF₄)₂, was used for a reaction with graphene oxide. Macrocyclic copper complex/graphene‐based composite materials were prepared and applied to the counter electrodes (CEs) of dye‐sensitized solar cells (DSSCs). As the level of the macrocyclic copper complex increased, the catalytic sites on the surface of the CE increased. The results showed that the device efficiency of the composite GO/Cu (1:10) CE was 7.61%, which was better than that of the Platinum (Pt) CE (7.04%). The device efficiency of the DSSC was enhanced effectively because the electrocatalytic activity of the CE was enhanced, and the interface impedance of the device was reduced. Therefore, the macrocyclic copper complex/graphene‐based composite materials may have the potential to replace traditional Pt to increase efficiency and reduce the fabrication cost of DSSCs.     

Isolation of a Cationic Platinum(II) σ‐Silane Complex

The platinum complex [Pt(I^tBuⁱPr′)(I^tBuⁱPr)][BAr^F] interacts with tertiary silanes to form stable (<0 °C) mononuclear Pt^II σ‐SiH complexes [Pt(I^tBuⁱPr′)(I^tBuⁱPr)(η¹‐HSiR₃)][BAr^F]. These compounds have been fully characterized, including X‐ray diffraction methods, as the first examples for platinum. DFT calculations (including electronic topological analysis) support the interpretation of the coordination as an unusual η¹‐SiH. However, the energies required for achieving a η²‐SiH mode are rather low, and is consistent with the propensity of these derivatives to undergo Si?H cleavage leading to the more stable silyl species [Pt(SiR₃)(I^tBuⁱPr)₂][BAr^F] at room temperature.     

Sensitively Electrochemical Sensing for Sequence‐Specific Detection of Phosphinothricin Acetyltransferase Gene: Layer‐by‐Layer Films of Poly‐L‐Lysine and Au‐Carbon Nanotube Hybrid

An electrochemical DNA sensing film was constructed based on the multilayers comprising of poly‐L ‐lysine (pLys) and Au‐carbon nanotube (Au‐CNT) hybrid. A precursor film of mercaptopropionic acid (MPA) was firstly self‐assembled on the Au electrode surface. pLys and Au‐CNT hybrid layer‐by‐layer assembly films were fabricated by alternately immersing the MPA‐modified electrode into the pLys solution and Au‐CNT hybrid solution. Cyclic voltammetry was used to monitor the consecutive growth of the multilayer films by utilizing [Fe(CN)₆]^3?/4? and [Co(phen)₃]^3+/2+ as the redox indicators. The outer layer of the multilayer film was the positively charged pLys, on which the DNA probe was easily linked due to the strong electrostatic affinity. The hybridization detection of DNA was accomplished by using methylene blue (MB) as the indicator, which possesses different affinities to dsDNA and ssDNA. Differential pulse voltammetry was employed to record the signal response of MB and determine the amount of the target DNA sequence. The established biosensor has high sensitivity, a relatively wide linear range from 1.0×10^?10 mol/L to 1.0×10^?6 mol/L and the ability to discriminate the fully complementary target DNA from single or double base‐mismatched DNA. The sequence‐specific DNA related to phosphinothricin acetyltransferase gene from the transgenically modified plants was successfully detected.     

A Soft‐Template‐Conversion Route to Fabricate Nanopatterned Hybrid Pt/Carbon for Potential Use in Counter Electrodes of Dye‐Sensitized Solar Cells

Hybrid Pt(platinum)/carbon nanopatterns with an extremely low loading level of Pt catalysts derived from block copolymer templates as an alternative type of counter electrodes (CEs) in dye‐sensitized solar cells (DSSCs) are proposed. DSSCs employing hybrid Pt/carbon with tailored configuration as CEs exhibit higher short‐circuit current and conversion efficiencies as well as stability with a lapse of time compared with conventional cells on the basis of sputtered Pt thin films, evidencing that the new class of hybrid nanostructures possess high potential for cost‐effective electrodes in energy conversion devices.

     

Scalable Low‐Cost SnS2 Nanosheets as Counter Electrode Building Blocks for Dye‐Sensitized Solar Cells

A new type of semitransparent SnS₂ nanosheet (NS) films were synthesized using a simple and environmentally friendly solution‐processed approach, which were subsequently used as a counter electrode (CE) alternative to the noble metal Pt for triiodide reduction in dye‐sensitized solar cells (DSSCs). The resultant SnS₂‐based CE with a thickness of about 300 nm exhibited excellent electrochemical catalytic activity for catalyzing the reduction of triiodide and demonstrated comparable power conversion efficiency of 7.64 % with that of expensive Pt‐based CE in DSSCs (7.71 %). When functionalized with a small amount of carbon nanoparticles, the SnS₂ NS‐based CE showed even better performance of 8.06 % than Pt under the same conditions. Considering the facile fabrication method, optical transparency, low cost, and remarkable catalytic property, this study on SnS₂ NSs may shed light on the large‐scale production of electrocatalytic electrode materials for low‐cost photovoltaic devices.     

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η2‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC1)platinum(II)]

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)platinum(II)], [Pt₂(C₁₅H₁₉O₄)₂Cl₂], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform–diethyl ether or methylene chloride–diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile‐κN)(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chloridoplatinum(II) monohydrate, [Pt(C₁₅H₁₉O₄)Cl(CH₃CN)]·H₂O, (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethylformamide‐κO)platinum(II), [Pt(C₁₅H₁₉O₄)Cl(C₂H₇NO)], and (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethyl sulfoxide‐κS)platinum(II), determined as the analogue {η²‐2‐allyl‐4‐methoxy‐5‐[(ethoxycarbonyl)methoxy]phenyl‐κC¹}chlorido(dimethyl sulfoxide‐κS)platinum(II), [Pt(C₁₄H₁₇O₄)Cl(C₂H₆OS)]. The crystal structures confirm that acetonitrile interacts with the Pt^II atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt—Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C—H…O and C—H…π interactions, but no π–π interactions are observed despite the presence of the aromatic ring.