Phenyl C61-butyric Acid Methyl Research Articles

A comparative study of PffBT4T-2OD/EH-IDTBR and PffBT4T-2OD/PC71BM organic photovoltaic heterojunctions

In order to clarify the different photovoltaic performance and “burn-in” degradation mechanism, the electron donor poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3′″-di(2-octyldodecyl)-2,2′;5′,2″;5″,2′″-quaterthiophen-5,5′″-diyl)] (PffBT4T-2OD), fullerene derivative acceptor [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) and the nonfullerene acceptor indacenodithiophene core flanked with benzothiadiazole and rhodanine groups with the branched (2-ethylhexyl) chains (coded as EH-IDTBR) were selected to construct PffBT4T-2OD/EH-IDTBR and PffBT4T-2OD/PC71BM complexes as heterojunction interface models. The geometries, electronic structures, excitation properties and the rates of electron processes were extensively explored based upon quantum chemistry calculations. The results indicate that the light harvesting capability of EH-IDTBR is far better than that of PC71BM. Most of excited states of PffBT4T-2OD and EH-IDTBR exhibit intramolecular charge transfer characters. Compared with PffBT4T-2OD/PC71BM, the better planarity, stronger non-bonding interactions, and the hybrid excited states, as well as the larger electrostatic potential difference between the donor and acceptor of PffBT4T-2OD/EH-IDTBR are responsible for its better photovoltaic performance and the lower “burn-in” degradation. Although the rates of charge recombination of PffBT4T-2OD/EH-IDTBR complex is larger, its faster rates of exciton dissociation and charge transfer processes can be helpful to resist “burn-in” degradation. The results are helpful to develop novel OPV materials that are resistant to “burn-in” degradation.

Photoinduced Resist-free Imprinting (PRI) in fullerene thin films as revealed by Grazing Incidence Small-angle X-ray scattering

In this article we explore the potential of synchrotron Grazing Incidence Small Angle X-ray Scattering (GISAXS) to evaluate the extension of a Photoinduced Resist-free Imprinting (PRI) effect for grating-like Laser Induced Periodic Surface Structures (LIPSS) on spin-coated thin films of the fullerene derivative [6,6]-phenyl C71-butyric acid methyl ester (PC71BM). Valuable information about the nature of both the original fullerene LIPSS and of the remaining resist-free nanostructure in terms of geometry, size distribution, lattice periodicity and degree of order can be achieved by simulations of the GISAXS patterns. One of the most interesting features provided by the GISAXS analysis is the estimation of the paracrystalline distortion factor, which can be useful to evaluate the level of order in the nanostructure. Data revealed that LIPSS in PC71BM films can be described as one-dimensional paracrystalline lattices with levels of order in accordance with those typically observed in LIPSS of other materials. The PRI effect leaves a qualitatively similar nanostructure but about two times more disordered than the original LIPSS one. Our results show that GISAXS is a powerful tool to characterize Resist-free Imprinting procedures of potential relevance in nanotechnology.

Sulfonate-Conjugated Polyelectrolytes as Anode Interfacial Layers in Inverted Organic Solar Cells.

Conjugated polymers with ionic pendant groups (CPEs) are receiving increasing attention as solution-processed interfacial materials for organic solar cells (OSCs). Various anionic CPEs have been successfully used, on top of ITO (Indium Tin Oxide) electrodes, as solution-processed anode interlayers (AILs) for conventional devices with direct geometry. However, the development of CPE AILs for OSC devices with inverted geometry is an important topic that still needs to be addressed. Here, we have designed three anionic CPEs bearing alkyl-potassium-sulfonate side chains. Their functional behavior as anode interlayers has been investigated in P3HT:PC61BM (poly(3-hexylthiophene): [6,6]-phenyl C61 butyric acid methyl ester) devices with an inverted geometry, using a hole collecting silver electrode evaporated on top. Our results reveal that to obtain effective anode modification, the CPEs’ conjugated backbone has to be tailored to grant self-doping and to have a good energy-level match with the photoactive layer. Furthermore, the sulfonate moieties not only ensure the solubility in polar orthogonal solvents, induce self-doping via a right choice of the conjugated backbone, but also play a role in the gaining of hole selectivity of the top silver electrode.

Modelling and Calculation of Characteristic Parameters of the Active and Buffer Layers in Organic Solar Cell

Background: The active layer not only must have a strong light absorption in the visible spectrum but must also be sufficient for charge carrier transport to the electrodes. Electrons in conducting polymer transport by hopping between different energy levels resulted in much lower charge mobility. Therefore, the thickness of the active layer must be limited, so the separated charge can reach the corresponding electrodes without recombination. However, a thin active layer has weaker light absorption, resulting in the low photogenerated current in organic solar cell devices. Furthermore, buffer layers usually have high charge mobility, which in turn would enhance the transportation of charge from the active layer to electrodes. Metal oxides have been studied to be used as a cathode buffer layer, such as titanium dioxide (TiO2), zinc oxide (ZnO), etc. Objective: In this work, behaviors of the photon-electrical characteristics with variation in thickness of the active (poly(3-hexylthiophene-2,5-diyl) and phenyl-C61 butyric acid methyl ester blend) and buffer (zinc oxide) layers were investigated. Methods: The influences of the thickness of the active and buffer layers on characteristic parameters of organic solar cells were investigated by solving the drift and diffusion equation with the photogenerated current given by the Hetch equation. Results: The optimum thickness was obtained around 100 nm and below 10 nm for the active and the ZnO buffer layers, respectively. Conclusion: Thinner active layer resulted in lower photocurrent due to poor light absorption while at 150 nm thick and above, PCE of the device reduced rapidly because of the high recombination rate of photogenerated electron-hole pairs. ZnO buffer layer was used as an electron transport layer and a hole blocking layer in order to improve the cell’s performance. The addition of ZnO enhanced the PCE up to 2.48 times higher than the conventional device.

Effect of 1,8-Diiodooctance additive on the charge carriers behavior in the PCPDTBT:PC71BM BHJ films investigated by using electric-field-induced optical second-harmonic generation measurement

Electric-field-induced optical second harmonic generation (EFISHG) measurement was conducted to investigate the effect of 1,8-diiodooctane (DIO) additive, which is relevant to improve the efficiency of bulk heterojunction (BHJ) solar cells, on carrier behaviors in the BHJ layer, where the BHJ layer is a blend of [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) and regioregular poly [2,6-(4,4-bis-(2-Ethylhexyl)-4H-cyclopentane [2,1-b;3,4-b′] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT). Using the laser wavelength of 1000 nm, we could selectively observe the electric field in the PCPDTBT phase of BHJ layer, which allowed us to determine the difference in charge accumulation at the interface with and without DIO. With adding DIO, a decrease in interfacial stored charge was observed, and this plays a role in improving the efficiency by about 25%. The DIO modified the internal field distribution so that the electric field promotes the electrons toward the ITO electrode and holes toward the PEDOT:PSS/Au electrode.

Morphology optimization of organic solar cells enabled by interface engineering of zinc oxide layer with a conjugated organic material

A diphenylphosphine-oxide-based conjugated organic molecule, ((1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl))tris(diphenylphosphine oxide) (PO-T2T), was doped into ZnO to improve the characteristics of the electron transport layer (ETL) in inverted organic solar cells (OSCs). A series of characterization techniques were carried out to demonstrate the function of PO-T2T in film aspect, including transmittance, atomic force microscopy (AFM), transmission electron microscopy (TEM), water contact angle and grazing incidence wide angle X-ray scattering (GIWAXS). Light dependent, space-charge-limited current, exciton dissociation possibility were aimed to explore the influence of PO-T2T for internal carrier behaviors based on PTB7-Th: PC 71 BM system. It's found that the PO-T2T doped ETLs played a role in morphology optimization of ETL and undermined the trap-assistant recombination through filling the defects ZnO itself had, simultaneously. Besides, the electron mobility was also improved. With the optimized functionalities, the OSCs' efficiency based on fullerene system Poly[4,8- bis(5-(2-Ethylhexyl)thiophen-2-yl) benzo [1,2-b:4,5-b′] dithiophene-co-3-fluorothieno [3,4-b] thiophene-2-carboxylate] (PTB7-Th): [6,6]-Phenyl C71 butyric acid methyl ester (PC 71 BM) was improved from 9.03% to 9.84%. Finally, when this strategy was applied into another hot-topic system, poly((2,6-(4,8-bis(5-(2-ethylhexyl-3- fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5- (1′,3′-di-2-thienyl)-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′] dithiophene-4,8-dione)) (PBDB-TF):2,2′-((2Z,2′Z)-((12,13-bis(2- ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e] thieno[2,″3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5] thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6), a high PCE of 16.34% was obtained. These results demonstrated that the PO-T2T had a positive role in OSC performance improvement. • OSCs based on PM6:Y6 achieved a PCE of 16.34% from 15.44%. • The morphology of PO-T2T doped ETL was more feasible for the form of the active layer. • The defects in ZnO were weakened and the electron collection was facilitated.

Carbon/graphene quantum dot and conjugated polymer nanostructures impart unprecedented high efficiencies in routine P3HT:PCBM photovoltaics

Graphene quantum dot (GQD) and carbon quantum dot (CQD) nanoparticles were employed to fabricate the crab-like GQD/poly(3-hexylthiophene) (P3HT) and semicrab-like CQD/P3HT short chain, pellet-like GQD/P3HT and CQD/P3HT long chain, GQD/P3HT nanofiber and CQD/P3HT nanofiber supramolecules. The P3HT crystals were composed of face-on ((100) and (002) prisms) and edge-on ((020) and (002) growth planes) oriented chains. The lowest d-spacing values were acquired for the QD decorated P3HT nanofibers (d(100) = 13.41–13.46 Ǻ and d(020) = 3.39–3.43 Ǻ). To investigate the function of designed supramolecules in roles of morphology modifier, donor, and acceptor, the ternary and binary photovoltaics of P3HT: (Meissner and Wohrle, 1991; Meissner and Wohrle, 1991)-Phenyl C71 butyric acid methyl ester (PC71BM):supramolecule, P3HT:supramolecule, and PC71BM:supramolecule were prepared. The GQD-based nanostructures acted better than the CQD-based ones, originated from their thinner and disk-like nature, and the highest photovoltaic characteristics were detected in P3HT:PC71BM:GQD/P3HT nanofiber systems (14.06 mA cm−2, 0.70 V, 66.11%), leading to a performance of 6.50%. Thin films modified by crab-like GQD/P3HT short chain (5.47%), CQD/P3HT nanofiber (4.56%), and semicrab-like CQD/P3HT short chain (3.46%) nanostructures also reflected the high-quality devices. The systems manipulated by the crab/semicrab-like (668 and 462 Ω.cm2) and decorated fibrillar (553 and 395 Ω.cm2) nanostructures demonstrated the faster electron transport and, thereby the lower carrier recombination. Even the well-designed supramolecules of GQD/P3HT nanofiber and crab-like GQD/P3HT short chain led to the low-quality binary photovoltaics (3.68% and 2.29%) with respect to corresponding ternary systems. When the QDs and their associated nano-hybrids were employed as the electron donors, the weakest cells were fabricated and the highest efficacy was 2.01% for PC71BM:GQD/P3HT.

Small Molecules with Controllable Molecular Weights Passivate Surface Defects in Air‐Stable p‐i‐n Perovskite Solar Cells

AbstractThe passivation of surface defects at the interfaces and grain boundaries of perovskites has great potential to improve the optoelectronic properties of related devices. In this study, the small molecules LG0.5, LG1.5, and LG2.5—having precise and controllable molecular weights (various generations synthesized through click reactions) and featuring urethane, urea, and malonamide functionalities—are synthesized, and their ability to passivate the defects of perovskites are evaluated. X‐ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and time‐resolved photoluminescence spectroscopy are used to observe the interactions between the perovskites and these molecules. The embedding of LG0.5 promotes the growth of large‐grain perovskite crystals, leading to increases in the intensities of the UV–vis absorption and photoluminescence spectral signals of the perovskite as well as longer carrier lifetimes. A power conversion efficiency of almost 20% for a p‐i‐n perovskite solar cell having the layer structure indium tin oxide/NiOx/CH3NH3PbI3 (with LG0.5)/[6,6]‐phenyl C61 butyric acid methyl ester/bathocuproine/Ag is observed. This device (without encapsulation) exhibits excellent air‐stability, retaining 89.8% of its initial performance after storage in an ambient environment (25 °C, 40% humidity) for over 120 d.

Lead-free and electron transport layer-free perovskite yarns: Designed for knitted solar fabrics

Highly flexible and Lead-free perovskite solar yarns, based on methylammonium tin mixed halide- Polyvinylpyrrolidone (PVP) composite nanofibers doped with [6,6]-Phenyl C61 butyric acid methyl ester (PC61BM), as the light harvesters are reported. The photoactive nanofiber layer of the solar yarn featured an optical bandgap of 1.65 eV, with a remarkable light absorption capacity > 90% in the wavelength range of 300–550 nm, outstanding flexibility, and an impressive charge carrier lifetime of 278 ns which rises to 300 ns upon doping with PC61BM. These photoactive nanofibers are directly electrospun on top of poly(3-hexylthiophene-2,5-diyl) ‘P3HT’, as the hole transporting layer, which was coated on a multi-filament carbon fiber yarn. The resulting yarn is twisted with a commercial silver yarn, serving as the positive electrode. The ensuing fiber-shaped solar device exhibits a maximum power conversion efficiency of 5.34% which is increased to 7.49% upon doping the photoactive layer with 0.17% PC61BM. A knitted solar fabric from the novel solar yarn with 45-mm × 35-mm active area presented a maximum power density of 1.21 mWcm−2 under 1 sun (1000 Wm−2) solar illumination.

The effect of polymer concentration in chloroform on P3HT:PCBM nanoparticulate organic photovoltaic device performance

Investigations about the effect of concentration of polymer (1:1 Poly (3-hexylthiophene) (P3HT):phenyl C61 butyric acid methyl ester (PCBM)) in chloroform have been performed. Six different concentrations varying from 36 mg/ml to 179 mg/ml, were used to prepare P3HT:PCBM nanoparticulate organic photovoltaic (NP-OPV) devices. Using Dynamic Light Scattering (DLS), KLA-Tencor Alpha Step 500 profilometer, UV-visible spectroscopy (UV-Vis), we analyze and optimize the concentration of polymer in chloroform in producing NP-OPV devices. Higher concentration resulting in a bigger size of nanoparticle and thicker thin film we have, so that affects the efficiency of NP-OPV devices. In this investigation, the highest efficiency was achieved when using a concentration of 54 mg/ml.

Fabrication of bulk heterojunction organic photovoltaic and effect of buffer layer on the basic solar cell parameters

The poly(3-hexylthiophene-2,5-diyl):phenyl C61 butyric acid methyl ester (P3HT:PCBM) organic material is important for BHJ organic solar cells. In this study PEDOT:PSS layer was coated on ITO using spin coater and thereon coated P3HT:PCBM (1:1) as fotoactive layer. Finally, Al contacts have been evaporated for electrical measurements and device structure completed. In other example, 2 nm LiF evaporated on P3HT:PCBM before metal. Electrical characterization of the devices performed with current density–voltage (J–V) measurement at room temperature and a solar simulator under an 100 mW/cm2 irradiation intensity. Basic solar cells parameters as short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF) and power conversion efficiency (PCE) of the organic solar cells were determined with the measurement. Efficiency of organic solar cells increased 0.85% to 1.87% using LiF as buffer layer. Similary, LiF layer was increased other parameters of device and obtained more stabil the device.

Electron and hole transport in solution-processed fullerenes

Methanofullerene [6,6]-phenyl C61-butyric acid methyl ester and its derivatives have been the workhorse acceptors in organic bulk heterojunction solar cells for more than two decades. Here, an overview of their charge transport properties is given.

Finite Element Numeric Simulation of Organic Solar Cells with Gold Thin Film

In this paper, we have explored the potential of organic solar cells with gold layers, simulating different geometries and comparing them with the experimental data obtained from the devices produced at the “optoelectronic organic devices laboratory at Ben Gurion University of the Negev, Israel.” Thin-film heterojunction solar devices are analyzed using a basic chemical technology of GLASS/ITO/PEDOT,PSS/P3HT, PCBM, and another type of nanostructure where the gold layer is added. A standard device is realized on top of a transparent substrate such as glass or flexible polymer Polyethylene Terephthalate (PET). The first layer is the anode, which is made of conductive material and is also transparent. In our case, the very common material Indium-Tin-Oxide (ITO) is used. To facilitate the transition between the active layer and the anode, an intermediate layer is introduced. Hole Transport Layer (HTL) 's high hole mobility allows holes to move towards the anode instead of the cathode. On top of these layers the organic active layer is constituted by a blend of two organic materials configuring a multiple junction morphology (Bulk Heterojunction or BHJ). In our case, two commonly organic materials [6,6]-Phenyl C61 Butyric acid Methyl ester and Poly(3-Hexylthiophene-2,5-diyl) (PCBM:P3HT) are used. The cathode on top organic active layer is made of highly conductive opaque metal, mostly Aluminum (Al). The finite-element method has been used to compute the electromagnetic field distributions. The results show that the model with the gold layer increases the electrical performance of organic solar cells.

Effect of precursor solution concentrations of PCBM interlayer between low-temperature spin-coating TiO2 electron transport layer and light absorption layer on physical properties of perovskite film and photo-current hysteresis of photo-voltaic devices

we insert (6,6)-phenyl c61 butyric acid methyl ester (PC61BM) interlayer of different precursor solution concentrations between low-temperature TiO2 electron transport layer (ETL) and light absorption layer to modify charge carrier transporting, mitigate hysteresis and improve perovskite film quality. The results show that the TiO2 / perovskite interface, the perovskite film morphology and photo physical properties can be modified by optimizing the precursor solution concentrations of PC61BM interlayer, which facilitates the electron extraction from perovskite absorption layer to TiO2 ETL and reduces the hysteresis.

Effect of Different Ionic Surfactants on the Structural, Photophysical, and Morphological Properties of Water‐Based P3HT:PCBM Nanoparticle Dispersions and Films

AbstractAqueous suspensions of composite nanoparticles of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) are fabricated by miniemulsion method using three different ionic surfactants. The aim is to study how the length and conformation of the surfactants alkyl chains affect the properties of the nanoparticles. While the morphology and dimensions of the nanoparticles are similar, UV–vis spectroscopy evidences that the internal aggregation and ordering of the P3HT chains varies within the three nanoparticle formulations. The surfactant with branched alkyl chains promote the highest degree of ordering of P3HT chains in the nanoparticles (leading to increased conjugation length). In contrast, the lowest ordering is found for the nanoparticles with the surfactant having the shortest linear alkyl chain. The optical/structural properties of nanoparticles are partially retained in the films. Besides, the surfactant with branched alkyl chains favors the strongest coalescence of nanoparticles in the thin film, promoting a further ordering of the polymeric chains in the most external shell of the nanoparticles as evidenced by steady‐state and time‐resolved UV–vis spectroscopy and confocal fluorescence microscopy. These findings might guide the engineering of new surfactants for composite nanoparticles for optoelectronic applications.

Role of DIO vis-à-vis microstructural kinetics during thermal annealing on the performance of PTB7:PC71BM organic solar cells

Thermal annealing is an important process to improve the power conversion efficiency (PCE) of bulk-hetero junction organic solar cells (BHJ OSCs) by inducing micro-structural changes within the active layer blend’s constituents leading to amelioration of charge transfer/transport dynamics and interfacial properties. This work investigates the impact of thermal annealing on the photovoltaic performance ofPoly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-Phenyl C71-butyric acidmethyl ester(PC71BM) (PTB7:PC71BM) thin film blend in the presence of DIO (1,8 –Diiodooctane) additive, at different annealing temperatures (40, 60 and 80 °C) and correlates with the performance of DIO-free devices investigated under similar annealing conditions. Our results show that DIO-containing (w/DIO)blends, annealed at moderate temperature (40 °C) for 1 h exhibit significantly improved short circuit current (Jsc)as well as fill factor (FF) and hence 25% improvement in PCE over bench dried (unannealed) DIO-containing blend films. Interestingly, thermal treatment of DIO containing blend films at a higher temperature of 80 °C results in significant reduction of FF. However, for without DIO (w/o DIO) devices, FF remains unchanged while decrease in Jsc is significant. The inferior performance of both (w/DIO and w/o DIO) the devices at higher temperatures ~80 °C emanates from an unfavorable distribution of the polymer- fullerene network, as shown by morphological and surface potential analyses. Specifically, in w/DIO devices, the decreased performance is possibly induced by the temperature driven, accelerated loss of DIO additive that produces the evolution of undesirable morphology thus deteriorating the performance.

Ultra‐Low Dark Current Organic–Inorganic Hybrid X‐Ray Detectors

AbstractOrganic‐inorganic hybrid semiconductors are an emerging class of materials for direct conversion X‐ray detection due to attractive characteristics such as high sensitivity and the potential to form conformal detectors. However, existing hybrid semiconductor X‐ray detectors display dark currents that are 1000–10 000× higher than industrially relevant values of 1–10 pA mm−2. Herein, ultra‐low dark currents of <10 pA mm−2, under electric fields as high as ≈4 V µm−1, for hybrid X‐ray detectors consisting of bismuth oxide nanoparticles (for enhanced X‐ray attenuation) incorporated into an organic bulk heterojunction consisting of p‐type Poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and n‐type [6,6]‐Phenyl C71 butyric acid methyl ester (PC70BM) are reported. Such ultra‐low dark currents are realized through the enrichment of the hole selective p‐type organic semiconductor near the anode contact. The resulting detectors demonstrate broadband X‐ray response including an exceptionally high sensitivity of ≈1.5 mC Gy−1 cm−2 and <6% variation in angular dependence response under 6 MV hard X‐rays. The above characteristics in combination with excellent dose linearity, dose rate linearity, and reproducibility over a broad energy range enable these detectors to be developed for medical and industrial applications.

Tailoring organic bulk-heterojunction for charge extraction and spectral absorption in CsPbBr3 perovskite solar cells

All-inorganic CsPbBr3 perovskite solar cells (PSCs) are promising candidates to balance the stability and efficiency issues of organic-inorganic hybrid devices. However, the large energy barrier for charge transfer and narrow spectral response are still two challenging problems for performance improvement. We present here an organic bulk-heterojunction {poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester (P3HT: PCBM)} photoactive layer to boost the charge extraction and to widen the spectral absorption, achieving an enhanced power conversion efficiency up to 8.94% by optimizing the thickness of P3HT: PCBM photoactive layer, which is much higher than 6.28% for the pristine CsPbBr3 device. The interaction between the carbonyl group in PCBM and unsaturated Pb atom in the perovskite surface can effectively passivate the defects and reduce charge recombination. Furthermore, the coupling effect between PCBM and P3HT widens the spectral response from 540 to 650 nm for an increased short-circuit current density. More importantly, the devices are relatively stable over 75 days upon persistent attack by 70% relative humidity in air condition. These advantages of high efficiency, excellent long-term stability, cost-effectiveness and scalability may promote the commercialization of inorganic PSCs.

Synthesis of small molecule dye additive for efficient and DIO-free ternary organic solar cells

A promising technique to enhance absorption of light in organic solar cells, “ternary approach” represents an important function in improving the device performance. We combined one small molecule dye (5,8-di(benzofuran-2-yl)-2,3-diphenylquinoxaline) (DB-Qx) with [6, 6]-phenyl C71 butyric acid methyl ester (PC71BM) (as the electron acceptor) and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiopheneco-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th)(as the electron donor polymer) to form ternary solar cells. The morphology of the active layer of the ternary blend and hole mobility was potentially enhanced by the addition of a molecular donor. The complementary absorption of the two donors and matching photo-luminesce overlapping of DB-Qx with PTB7-Th contributed to improving the device performance. This means that the molecular donor in the ternary blend has an active function in the morphology. The devices produced PCE of 8.64% in the ternary blend system relative to 5.98% in the binary blend system. And, since the emission of DB-Qx partially overlaps with the absorption of PTB7Th, the transfer of energy from DB-Qx to PTB7-TH can improve the exciton utilization efficiency and achieve enhanced overall power conversion efficiency in this ternary solar cell. In this study, we synthesized a small fluorescent molecule material and constructed efficient ternary blend PSCs. Remarkably, the inverted device DIO-free ternary solar cells boost PCE from 5.98 to 8.64% and also exhibit the combined improvement in JSC and the morphology compared to those of DIO-processed films.

High-Performance Inverted Structure Broadband Photodetector Based on ZnO Nanorods/PCDTBT:PCBM:PbS QDs

This article reports the performance improvement of a broadband photodetector using penetrating ZnO nanorods arrays (NRAs)-based electron transport layer (ETL) into a nanocomposite active layer of poly-[N-9''-heptadecanyl-2.7-carbazole-alt-5.5(4',7'-di-2-thienyl-2',1',3 -benzothiadiazole)] (PCDTBT), [6,6]-phenyl C61 butyric acid methyl ester (PCBM), and PbS quantum dots (QDs) grown on an fluorine-doped tin oxide (FTO)-coated glass substrate. A thin layer of MoOx on the active layer was used as the hole transport layer (HTL) of the proposed photodetector. The device showed a high responsivity of ~213.77, ~28.57, and ~7.22 A/W at three selected wavelengths in ultraviolet (380 nm), visible (550 nm), and near-infrared (860 nm) regions, respectively. High external quantum efficiency (EQE) of more than 1000% was measured for each selected wavelength at low -1.5 V external bias. The superior EQE in the proposed device was attributed to both the surface trap-induced carrier injection into the ZnO NRA and ultrafast exciton dissociation existing in the PCDTBT:PCBM system.