Advancements and Prospects in Perovskite Solar Cells: From Hybrid to All-Inorganic Materials.

Hybrid perovskites, materials composed of metals and organic substances in their structure, have emerged as potential materials for the new generation of photovoltaic cells due to a unique combination of optical, excitonic and electrical properties. Inspired by sensitization techniques on TiO2 substrates (DSSC), CH3NH3PbBr3 and CH3NH3PbI3 perovskites were studied as a light-absorbing layer as well as an electron-hole pair generator. Photovoltaic cells based on per-ovskites have electron and hole transport layers (ETL and HTL, respectively), separated by an ac-tive layer composed of perovskite itself. Major advances subsequently came in the preparation methods of these devices and the development of different architectures, which resulted in an efficiency exceeding 23% in less than 10 years. Problems with stability are the main barrier to the large-scale production of hybrid perovskites. Partially or fully inorganic perovskites appear promising to circumvent the instability problem, among which the black perovskite phase CsPbI3 (α-CsPbI3) can be highlighted. In more advanced studies, a partial or total substitution of Pb by Ge, Sn, Sb, Bi, Cu or Ti is proposed to mitigate potential toxicity problems and maintain device efficiency.

Scanning Tunneling Spectroscopy Method for the Prediction of Semiconductor Heterojunction Performance as a Prequel for Device Development.

The prediction of semiconductor device performance is a persistent challenge in materials science, and the ability to anticipate useful specifications prior to construction is crucial for enhancing the overall efficiency. In this study, we investigate the constituents of a solar cell by employing scanning tunneling microscopy (STM) and spectroscopy (STS). Through our observations, we identify a spatial distribution of the dopant type in thin films of materials that were designed to present major p-doping for germanium sulfide (GeS) and dominant n-doping for tin disulfide (SnS2). By generating separate STS maps for each semiconductor film and conducting a statistical analysis of the gap and doping distribution, we determine intrinsic limitations for the solar cell efficiency that must be understood prior to processing. Subsequently, we fabricate a solar cell utilizing these materials (GeS and SnS2) via vapor phase deposition and carry out a characterization using standard J-V curves under both dark/illuminated irradiance conditions. Our devices corroborate the expected reduced efficiency due to doping fluctuation but exhibit stable photocurrent responses. As originally planned, quantum efficiency measurements reveal that the peak efficiency of our solar cell coincides with the range where the standard silicon solar cells sharply decline. Our STS method is suggested as a prequel to device development in novel material junctions or deposition processes where fluctuations of doping levels are retrieved due to intrinsic material characteristics such as the occurrence of defects, roughness, local chemical segregation, and faceting or step bunching.

Analytical Modeling and Optimization of Cu2ZnSn(S,Se)4 Solar Cells with the Use of Quantum Wells under the Radiative Limit.

In this work, we present a theoretical study on the use of Cu2ZnSn(S,Se)4 quantum wells in Cu2ZnSnS4 solar cells to enhance device efficiency. The role of different well thickness, number, and S/(S + Se) composition values is evaluated. The physical mechanisms governing the optoelectronic parameters are analyzed. The behavior of solar cells based on Cu2ZnSn(S,Se)4 without quantum wells is also considered for comparison. Cu2ZnSn(S,Se)4 quantum wells with a thickness lower than 50 nm present the formation of discretized eigenstates which play a fundamental role in absorption and recombination processes. Results show that well thickness plays a more important role than well number. We found that the use of wells with thicknesses higher than 20 nm allow for better efficiencies than those obtained for a device without nanostructures. A record efficiency of 37.5% is achieved when 36 wells with a width of 50 nm are used, considering an S/(S + Se) well compositional ratio of 0.25.

New Benzotrithiophene-Based Molecules as Organic P-Type Semiconductor for Small-Molecule Organic Solar Cells.

A new benzotrithiophene-based small molecule, namely 2,5,8-Tris[5-(2,2-dicyanovinyl)-2-thienyl]-benzo[1,2-b:3,4-b':6,5-b″]-trithiophene (DCVT-BTT), was successfully synthesized and subsequently characterized. This compound was found to present an intense absorption band at a wavelength position of ∼544 nm and displayed potentially relevant optoelectronic properties for photovoltaic devices. Theoretical studies demonstrated an interesting behavior of charge transport as electron donor (hole-transporting) active material for heterojunction cells. A preliminary study of small-molecule organic solar cells based on DCVT-BTT (as the P-type organic semiconductor) and phenyl-C61-butyric acid methyl ester (as the N-type organic semiconductor) exhibited a power conversion efficiency of 2.04% at a donor: acceptor weight ratio of 1:1.

pH-Effect in the Fabrication of ZnO Nanostructured Thin Films by Chemical Bath Deposition for Increasing the Efficiency of Solar Cells.

In this study, the impact of pH on the production of ZnO nanostructured thin films using chemical bath deposition was investigated for the purpose of enhancing the efficiency of solar cells. The ZnO films were directly deposited onto glass substrates at various pH levels during the synthesis process. The results indicate that the crystallinity and overall quality of the material were not affected by the pH solution, as observed through X-ray diffraction patterns. However, scanning electron microscopy revealed that surface morphology improved with increasing pH values, leading to changes in the size of the nanoflowers between pH 9 and 11 values. Furthermore, the ZnO nanostructured thin films synthesized at pH levels of 9, 10, and 11 were utilized in the fabrication of dye-sensitized solar cells. The ZnO films synthesized at pH 11 exhibited superior characteristics in short-circuit current density and open-circuit photo-voltage compared with those produced at lower pH values.

Construction and characterization of organic photovoltaic cells sensitized by Chrysanthemum based natural dye.

In this work, natural dyes from three different species of the same flower family (Chrysanthemum), which containing anthocyanin were extracted and properly prepared to be used as photosensitizers in DSSCs construction. The cells were fabricated with titanium dioxide nanoparticles (TiO2) for the photoanodes, whereas platinum electrodes were used for the photocathodes. To understand the behavior of light absorption in addition to the coloring components present in the dyes and the molecular functional groups present in the samples, the UV-Vis absorption spectroscopy and FTIR spectroscopy were used respectively. The performance and efficiency of solar cells were evaluated to establish the photovoltaic criteria for each DSSC built. Through electrochemical characterizations, it was possible to notice that the highest photovoltaic conversion efficiency was obtained with the Chrysanthemum Violet (CV) cell, with efficiency (η) of 1.348%, compared to 1.229% and 0.485% for the Chrysanthemum Green (CG) and Chrysanthemum Blue (CB) cells, respectively. The CV cell also has the highest open circuit voltage (VOC) at 0.58 V. The results corroborate to present the organic solar cells as a viable option for the electric energy generation.

Incorporation of Conjugated Diynes in Perovskites and their Post-Synthetic Modification.

Two-dimensional (2D) organic-inorganic hybrid perovskites have rapidly become an attractive alternative to three-dimensional (3D) perovskites as solar cell absorbers, owing to their improved stability, versatility, and ease of processing. Despite their advantages, the insulating nature of the organic cations makes these materials have lower absorbing and conducting properties, resulting in lower device efficiencies. A way to circumvent these issues is the integration of functional molecules that help mitigate these limitations. In this study, six new perovskites composed of three distinct diynes are synthesized, all of which can be thermally polymerized to form conjugated polymers within the perovskite layers. The incorporation of conjugated polymers results in drastic changes in these materials' optoelectronic properties and their overall stability. Furthermore, depending on the nature of the diyne and the inorganic layers, the materials show varying polymerization yields, optical bandgaps, and charge carrier densities. These results afford significant insight into the chemical nature of the polymerized species and thus highlight the versatility of this approach to post-synthetically generate conducting polymers within the layers of 2D perovskites, paving the way toward their use in optoelectronic devices.

New Benzotriazole and Benzodithiophene-Based Conjugated Terpolymer Bearing a Fluorescein Derivative as Side-Group: In-Ternal Förster Resonance Energy Transfer to Improve Organic Solar Cells.

A new benzodithiophene and benzotriazole-based terpolymer bearing a fluorescein derivative as a side group was synthesized and studied for organic solar cell (OSC) applications. This side group was covalently bounded to the backbone through an n-hexyl chain to induce the intramolecular Förster Resonance Energy Transfer (FRET) process and thus improve the photovoltaic performance of the polymeric material. The polymer exhibited good solubility in common organic chlorinated solvents as well as thermal stability (TDT10% > 360 °C). Photophysical measurements demonstrated the occurrence of the FRET phenomenon between the lateral group and the terpolymer. The terpolymer exhibited an absorption band centered at 501 nm, an optical bandgap of 2.02 eV, and HOMO and LUMO energy levels of −5.30 eV and −3.28 eV, respectively. A preliminary study on terpolymer-based OSC devices showed a low power-conversion efficiency (PCE) but a higher performance than devices based on an analogous polymer without the fluorescein derivative. These results mean that the design presented here is a promising strategy to improve the performance of polymers used in OSCs.

Optimization of N-PERT Solar Cell under Atacama Desert Solar Spectrum.

In the Atacama Desert, the spectral distribution of solar radiation differs from the global standard, showing very high levels of irradiation with a particularly high ultraviolet content. Additionally, the response of photovoltaic (PV) technologies is spectrally dependent, so it is necessary to consider local conditions and type of technology to optimize PV devices since solar cells are usually designed for maximum performance under standard testing conditions (STC). In this work, we determined geometrical and doping parameters to optimize the power of an n-type bifacial passivated emitter and rear totally diffused solar cell (n-PERT). Six parameters (the thicknesses of cell, emitter, and back surface field, as well as doping concentration of emitter, base, and back surface field) were used to optimize the cell under the Atacama Desert spectrum (AM 1.08) and under standard conditions (AM 1.5) through a genetic algorithm. To validate the model, the calculated performance of the n-PERT cell was compared with experimental measurements. Computed and experimental efficiencies showed a relative difference below 1% under STC conditions. Through the optimization process, we found that different geometry and doping concentrations are necessary for cells to be used in the Atacama Desert. Reducing the thickness of all layers and increasing doping can lead to a relative increment of 5.4% in the cell efficiency under AM 1.08. Finally, we show the potential effect of metallization and the viability of reducing the thicknesses of the emitter and the back surface field.

Boosting photovoltaic performance for Sb2S3solar cells by ionic liquid-assisted hydrothermal synthesis.

Bulk and surface trap-states in the Sb2S3films are considered one of the crucial energy loss mechanisms for achieving high photovoltaic performance in planar Sb2S3solar cells. Because ionic liquid additives offer interesting physicochemical properties to control the synthesis of inorganic material, in this work we propose the addition of 1-Butyl-3-methylimidazolium hydrogen sulfate (BMIMHS) into a Sb2S3hydrothermal precursor solution as a facile way to fabricate low-defect Sb2S3solar cells. Lower presence of small particles on the surface, as well as higher crystallinity are demonstrated in the BMIMHS-assisted Sb2S3films. Moreover, analyses of dark current density-voltageJ-Vcurves, surface photovoltage transient and intensity-modulated photocurrent spectroscopy have suggested that adding BMIMHS results in high-quality Sb2S3films and a successful defect passivation. Consequently, the best-performing BMIMHS-assisted device exhibits a 15.4% power conversion efficiency enhancement compared to that of control device. These findings show that ionic liquid BMIMHS can effectively be used to obtain high-quality Sb2S3films with low-defects and improved optoelectronic properties.

Organic Electronics from Nature: Computational Investigation of the Electronic and Optical Properties of the Isomers of Bixin and Norbixin Present in the Achiote Seeds.

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of photovoltaics. We performed density functional theory calculations to investigate the electronic and optical properties of the four natural dyes found in achiote seeds (Bixa orellana L.). Different DFT functionals, and basis sets, were used to calculate the electronic and optical properties of the bixin, norbixin, and their trans-isomers (molecules present in Bixa orellana L.). We observed that the planarity of the molecules and their similar extension for the conjugation pathways provide substantially delocalized wavefunctions of the frontier orbitals and similar values for their energies. Our findings also revealed a strong absorption peak in the blue region and an absorption band over the visible spectrum. These results indicate that Bixa orellana L. molecules can be good candidates for improving light-harvesting in photovoltaics.

In Situ Ethanolamine ZnO Nanoparticle Passivation for Perovskite Interface Stability and Highly Efficient Solar Cells.

Zinc oxide (ZnO) has interesting optoelectronic properties, but suffers from chemical instability when in contact with perovskite interfaces; hence, the perovskite deposited on the top degrades promptly. Surface passivation strategies alleviate this instability issue; however, synthesis to passivate ZnO nanoparticles (NPs) in situ has received less attention. Here, a new synthesis at low temperatures with an ethanolamine post treatment has been developed. By using ZnO NPs prepared with ethanolamine and butanol (BuOH), (E-ZnO), the stability of the FA0.9Cs0.1PbI3 (FACsPI)−ZnO interface was achieved, with a photoconversion efficiency of >18%. Impedance spectroscopy demonstrates that the recombination at the interface was reduced in the system with E-ZnO/perovskite compared to common SnO2/perovskite and that the quality of the perovskite on the top is clearly due to the ZnO in situ passivation with ethanolamine. This work extends the use of E-ZnO as an n-type charge extraction layer and demonstrates its feasibility with methylammonium perovskite. Moreover, this study paves the way for other in situ passivation methods with different target molecules, along with new insights regarding the perovskite interface rearrangement when in contact with the modified electron transport layer (ETL).

Recent Advances in Hole-Transporting Layers for Organic Solar Cells.

Global energy demand is increasing; thus, emerging renewable energy sources, such as organic solar cells (OSCs), are fundamental to mitigate the negative effects of fuel consumption. Within OSC's advancements, the development of efficient and stable interface materials is essential to achieve high performance, long-term stability, low costs, and broader applicability. Inorganic and nanocarbon-based materials show a suitable work function, tunable optical/electronic properties, stability to the presence of moisture, and facile solution processing, while organic conducting polymers and small molecules have some advantages such as fast and low-cost production, solution process, low energy payback time, light weight, and less adverse environmental impact, making them attractive as hole transporting layers (HTLs) for OSCs. This review looked at the recent progress in metal oxides, metal sulfides, nanocarbon materials, conducting polymers, and small organic molecules as HTLs in OSCs over the past five years. The endeavors in research and technology have optimized the preparation and deposition methods of HTLs. Strategies of doping, composite/hybrid formation, and modifications have also tuned the optical/electrical properties of these materials as HTLs to obtain efficient and stable OSCs. We highlighted the impact of structure, composition, and processing conditions of inorganic and organic materials as HTLs in conventional and inverted OSCs.

Triazine: An Important Building Block of Organic Materials for Solar Cell Application.

Since the beginning of the 21st century, triazine-based molecules have been employed to construct different organic materials due to their unique optoelectronic properties. Among their applications, photovoltaics stands out because of the current need to develop efficient, economic, and green alternatives to energy generation based mainly on fossil fuels. Here, we review all the development of triazine-based organic materials for solar cell applications, including organic solar cells, dye-sensitized solar cells, and perovskite solar cells. Firstly, we attempt to illustrate the main synthetic routes to prepare triazine derivatives. Then, we introduce the main aspects associated with solar cells and their performance. Afterward, we discuss different works focused on the preparation, characterization, and evaluation of triazine derivatives in solar cells, distinguishing the type of photovoltaics and the role of the triazine-based material in their performance (e.g., as a donor, acceptor, hole-transporting material, electron-transporting material, among others). Throughout this review, the progress, drawbacks, and main issues of the performance of the mentioned solar cells are exposed and discussed. Finally, some conclusions and perspectives about this research topic are mentioned.

Analysis, Synthesis and Characterization of Thin Films of a-Si:H (n-type and p-type) Deposited by PECVD for Solar Cell Applications.

In this paper, the analysis, synthesis and characterization of thin films of a-Si:H deposited by PECVD were carried out. Three types of films were deposited: In the first series (00 process), an intrinsic a-Si:H film was doped. In the second series (A1-A5 process), n-type samples were doped, and to carry this out, a gas mixture of silane (SiH4), dihydrogen (H2) and phosphine (PH3) was used. In the third series (B1-B5 process), p-type samples were doped using a mixture of silane (SiH4), dihydrogen (H2) and diborane (B2H6). The films' surface morphology was characterized by atomic force microscopy (AFM), while the analysis of the films was performed by scanning electron microscopy (SEM), and UV-visible ellipsometry was used to obtain the optical band gap and film thickness. According to the results of the present study, it can be concluded that the best conditions can be obtained when the flow of dopant gases (phosphine or diborane) increases, as seen in the conductivity graphs, where the films with the highest flow of dopant gas reached the highest conductivities compared to the minimum required for materials made of a-Si:H silicon for high-quality solar cells. It can be concluded from the results that the magnitude of the conductivity, which increased by several orders, represents an important result, since we could improve the efficiency of solar cells based on a-Si:H.

An Experimental and Theoretical Study of Dye Properties of Thiophenyl Derivatives of 2-Hydroxy-1,4-naphthoquinone (Lawsone).

A prospective study of the dye properties of non-toxic lawsone thiophenyl derivatives, obtained using a green synthetic methodology allowed for the description of their bathochromic shifts in comparison to those of lawsone, a well-known natural pigment used as a colorant that recently also has aroused interest in dye-sensitized solar cells (DSSCs). These compounds exhibited colors close to red, with absorption bands in visible and UV wavelength range. The colorimetric study showed that these compounds exhibited a darker color than that of lawsone within a range of colors depending on the substituent in the phenyl ring. Computational calculations employing Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT), showed that the derivatives have lower excitation energies than lawsone, while the alignment of their frontier orbitals regarding the conduction bands of TiO2 and ZnO and the redox potential of the electrolyte I-/I3- suggests that they could be employed as sensitizers. The study of the interactions of the lawsone and a derivative with a TiO2 surface model by different anchoring modes, showed that the adsorption is thermodynamically favored. Natural bond orbital (NBO) analysis indicates a two-center bonding (BD) O-Ti as the main interaction of the dyes with TiO2.

Extinction Coefficient Modulation of MoO3 Films Doped with Plasmonic Nanoparticles: From an Effective Medium Theory Description.

This work focused on the application of the effective medium theory to describe the extinction coefficient (Qext) in molybdenum trioxide (MoO3) doped with different kinds of plasmonic nanoparticles, such as silver (Ag), gold (Au), and copper (Cu). Usually, in studies of these materials, it is normal to analyze the transmission or absorption spectra. However, the effect of this type or size of nanoparticles on the spectra is not as remarkable as the effect that is found by analyzing the Qext of MoO3. It was shown that the ß-phase of MoO3 enhanced the intensity response of the Qext when compared to the α-phase of MoO3. With a nanoparticle size of 5 nm, the Ag-doped MoO3 was the configuration that presents the best response in Qext. On the other hand, Cu nanoparticles with a radius of 20 nm embedded in MoO3 was the configuration that presented intensities in Qext similar to the cases of Au and Ag nanoparticles. Therefore, implementing the effective medium theory can serve as a guide for experimental researchers for the application of these materials as an absorbing layer in photovoltaic cells.

Selenophene-Based Hole-Transporting Materials for Perovskite Solar Cells.

Two novel and simple donor-π-bridge-donor (D-π-D) hole-transporting materials (HTMs) containing two units of the p-methoxytriphenylamine (TPA) electron donor group covalently bridged by means of the 3,4-dimethoxyselenophene spacer through single and triple bonds are reported. The optoelectronic and thermal properties of the new selenium-containing HTMs have been determined using standard experimental techniques and theoretical density functional theory (DFT) calculations. The selenium-based HTMs have been incorporated in mesoporous perovskite solar cells (PSCs) in combination with the triple-cation perovskite [(FAPbI3 )0.87 (MAPbBr3 )0.13 ]0.92 [CsPbI3 ]0.08 . Limited values of power conversion efficiencies, up to 13.4 %, in comparison with the archetype spiro-OMeTAD (17.8 %), were obtained. The reduced efficiencies showed by the new HTMs are attributed to their poor film-forming ability, which constrains their photovoltaic performance due to the appearance of structural defects (pinholes).

Innovative Implementation of an Alternative Tetrathiafulvene Derivative for Flexible Indium Phthalocyanine Chloride-Based Solar Cells.

Herein, we present the photovoltaic properties of an indium phthalocyanine chloride (InClPc)-based flexible planar heterojunction device, introducing the tetrathiafulvene derivative 4,4'-Dimethyl-5,5'-diphenyltetrathiafulvalene (DMDP-TTF) as the electron donor layer. UV-vis spectroscopy is widely used to characterize the electronic behavior of the InClPc/DMDP-TTF active layer. The interactions between the DMDP-TTF and phthalocyanine are predominantly intermolecular and the result of the aggregation of InClPc. Tauc bands were obtained at 1.41 and 2.8 eV; these energy peaks can result in a charge transfer ascribed to the transition from the DMDP-TTF to π-orbitals that are associated with the phthalocyanine ring or even with the same indium metal center. Conductive carbon (CC) was used for the cathode. Finally, an indium tin oxide (ITO)/InClPc/DMDP-TTF/CC device was fabricated by high-vacuum thermal evaporation onto a flexible substrate and the photovoltaic properties were evaluated. A diode type I-V curve behavior was observed with a photovoltaic response under illumination. A generated photocurrent of 2.25 × 10-2 A/cm2 was measured. A conductivity reduction with the incident photon energy from 1.61 × 10-7 S/cm to 1.43 × 10-7 S/cm is observed. The diode resistance presents two different behaviors with the applied voltage. A VTFL of 5.39 V, trap concentration of 7.74 × 1016 cm-3, and carrier mobility values of ~10-6 cm2/V s were calculated, showing improved characteristics via the innovative implementation of an alternative TTF-derivative, indicating that the DMDP-TTF has a strong interaction at the junction where free available states are increased, thus inducing higher mobilities due to the large number of π-orbitals, which indicates the feasibility of its use in solar cells technology.

Synthesis and characterization of C60 and C70 acetylace-tone monoadducts and study of their photochemical properties for potential application in solar cells / Síntesis y caracterización de monoaductos de C60 y C70 con acetilacetona y estudio de sus propiedades fotoquímicas para su posible aplicación en células solares / Sínteses e caracterização de monoadutos de C60 e C70 com acetilacetona e estudo das suas propriedades fotoquímicas para a sua possível aplicação em células solares

Abstract We report on the synthesis of C60 and C70 monoadducts at room temperature through the Bingel reaction; employing acetylacetone as ligand; in presence of DBU (1,8-Diazabicyclo [5.4.0] undec-7-ene), carbon tetrabromide (CBr4), and o-dichlorobenzene. Diacetylmethane-[C60-Ih]-fullerene-[5,6] and diacetylmethane-[C70-D5h]-fullerene-[5,6] monoadducts were obtained with yields of 69% and 44%, respectively. The products were purified by column chromatography (CC, on silica gel, using hexane, carbon disulfide, and chloroform as eluents at room temperature) and characterized by Nuclear Magnetic Resonance ('H and 13C), Fourier-Transform Infrared (FT-IR) and UV-Visible spectroscopies, Matrix-assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) Mass spectrometry, Cyclic Voltammetry (CV), and Osteryoung Square Wave Voltammetry (OSWV). Both compounds showed irreversible reduction peaks controlled by diffusion, with LUMO energy levels of -3.09 eV, -3.13 eV for C60, and C70 monoadducts, respectively. These values are comparable with the -3.99 eV of PC61BM. The synthetized adducts were incorporated into inverted-type perovskite solar cells and were used as electron transporting materials (ETM) obtaining power conversion efficiencies (PCE) of 8.5% and 14.0% for the C60 and C70 monoadducts, respectively. When C60 is replaced by a lower symmetrical fullerene such as C70 an improved light absorption in the visible region is observed.

Resumen Reportamos la síntesis de monoadductos de C60 y C70 a temperatura ambiente a través de la reacción de Bingel, empleando acetilacetona como ligando, en presencia de DBU (1,8-diazabiciclo [5.4.0] undec-7-eno), tetrabromuro de carbono (CBr4) y o-diclorobenceno. Se obtuvieron monoadductos de diacetilmetano-[C -I.]-fullereno-[5,6] y diacetilmetano-[C70-D5h]-fullereno-[5,6] con rendimientos del 69% y 44%, respectivamente. Los productos se purificaron por cromatografía en columna (CC, usando silica gel, hexano, disulfuro de carbono y cloroformo como fase móvil, a temperatura ambiente) y se caracterizaron por resonancia magnética nuclear (1H y 13C), infrarrojo con transformada de Fourier (FT-IR), espectroscopia UV-Visible, espectrometría de masas, desorción/ionización láser asistida por matriz - tiempo de vuelo (MALDI-TOF), voltametría cíclica (CV) y voltametría de onda cuadrada de Osteryoung (OSWV). Ambos compuestos mostraron picos de reducción irreversibles controlados por difusión, con niveles de energía LUMO de -3,09 eV y -3,13 eV para los monoadductos C60 y C70, respectivamente. Estos valores son comparables con el -3,99 eV de PC61BM. Los aductos sintetizados se incorporaron a las células solares de perovskita de tipo inversa y se usaron como materiales de transporte de electrones (ETM) obteniendo eficiencias de conversión de energía (PCE) de 8,5% y 14,0% para los monoaductos C60 y C70, respectivamente. Cuando el C60 se reemplaza por un fullereno menos simétrico como el C70, se observa una absorción de luz mejorada en la región visible.

Resumo Reportamos a sínteses de monoadutos de C60 e C70 a temperatura ambiente através da reação de Bingel, utilizando acetilacetona como ligando, na presença de DBU (1,8-diazabiciclo [5.4.0] undec-7-eno), tetrabromuro de carbono (CBr4) e o-diclorobenzeno. Foram obtidos monoadutos de diacetilmetano-[C60-IJ-fulereno-[5,6] e diacetilmetano-[C70-D5J-fulereno-[5,6] com rendimentos de 69% e 44%, respectivamente. Os produtos se purificaram por cromatografia em coluna (CC, usando sílica gel, hexano, dissulfeto de carbono e clorofórmio como fase móvel à temperatura ambiente ) e se caracterizaram por ressonância magnética nuclear OH e 13C), infra-vermelho com transformada de Fourier (FT-IR), espectroscopia UV-Visível, espectrometria de massas, ionização e dessorção a laser assistida por matriz-tempo de voo (MALDI-TOF), voltametria cíclica (CV) e voltametria de onda quadrada de Osteryoung (OSWV). Ambos compostos mostraram picos de redução irreversíveis controlados por difusão, com níveis de energia LUMO de -3,09 eV, -3,13 eV para os monoadutos C60 e C70, respectivamente. Estos valores são comparáveis com -3,99 eV de PC61BM. Os adutos sintetizados se incorporaram nas células solares de perovskita de tipo inversa e se usaram como materiais de transporte de eletrões (ETM) obtendo eficiências de conversão de energia (PCE) de 8,5% e 14,0% para os monoadutos C60 e C70, respectivamente. Quando o C60 se substitui por um fulereno menos simétrico como o C70, se observa uma absorção de luz melhorado na região visível.