C61-butyric Acid Methyl Ester Research Articles

Influence of Top Layer Composition on the Photovoltaic Parameters of P3HT:PCBM Organic Solar Cells

Spin and spray deposition techniques have been used sequentially to examine the effect of the composition of top blend layer on the photovoltaic properties of organic solar cells using well-known poly(3-hexylthiophene):[6,6]-Phenyl C61 butyric acid methyl ester (P3HT:PCBM) blend. Devices were prepared by spraying an extra layer of P3HT or PCBM (~15 nm) onto spin coated (1:1) blend film. P3HT-rich top phase slightly perturbs photovoltaic activity whereas PCBM-rich top phase drastically changes the power conversion efficiencies with a marked decrease in fill factors. Carrier mobilities were only marginally affected by the presence of spray coated top layers. However, series resistance of top phase P3HT-rich blends remained the same with respect to spin coated sample whereas top phase PCBM-rich blends exhibit relatively higher series resistances for both annealed and non-annealed samples. Based on the presented results, one might speculate that electron injection to cathode with P3HT is almost as efficient as with PCBM for active layers utilizing P3HT:PCBM blend.

Synthesis and Photovoltaic Properties of New Conjugated D‐A Polymers Based on the Same Fluoro‐Benzothiadiazole Acceptor Unit and Different Donor Units

AbstractIn this work, two D−A conjugated polymers having same fluorinated benzothiadiazole acceptor and thiophene linker and different donor units (2,8‐dibromo‐4,6‐bis9n‐octylthiophene‐2‐yl)benzo(2,1‐b:3,4‐b’:5,6‐c”] trithiophene for P95 and 5,8‐dibromo‐2‐[5‐2(‐ethylhexyl)thiophene‐2yl]‐1H bisthieno[3,2‐e:2‘,3‘‐g]benzothiazole for P96 were synthesized. These polymers have complementary absorption spectra with both phenyl C71 butyric acid methyl ester (PC71BM) and non‐fullerene acceptor (PDIF) and energy levels for the exciton dissociation and charge transfer. After the optimization, the P95:PDIF and P96:PDIF based polymer solar cells showed overall PCE of showed 9.40% and 9.18% with energy loss of 0.54 eV and 0.64 eV, respectively which is higher than that of PC71BM counterpart (8.34% and 7.82% for P95 and P96, respectively). The higher values of short circuit current (Jsc) and open circuit voltage (Voc) and related to strong absorption of PDIF in 400–600 nm wavelength region and shallow value of lowest unoccupied molecular orbital (LUMO) energy level of PDIF. The higher value of power conversion efficiency of polymer solar cells based on P95, for both PC71BM and PDIF is related to the broader absorption spectra of P95 (low optical bandgap) as compared to P96 and more balanced charge transport due to higher hole mobility for P95 based active layer. These results demonstrate that the electron donating ability of donor unit in the D−A conjugated polymers may affect the photovoltaic response of the polymer solar cells and provide the guidance for the design of high efficiency photovoltaic materials.

Crystal-structure of active layers of small molecule organic photovoltaics before and after solvent vapor annealing

Abstract It is demonstrated by a detailed structural analysis that the crystallinity and the efficiency of small molecule based organic photovoltaics can be tuned by solvent vapor annealing (SVA). Blends made of the small molecule donor 2,2′-[(3,3′″,3″″,4′-tetraoctyl[2,2′:5′,2″:5″,2′″:5′″,2″″-quinquethiophene]-5,5″″-diyl)bis[(Z)-methylidyne(3-ethyl-4-oxo-5,2-thiazolidinediylidene)]]bis-propanedinitrile (DRCN5T) and the acceptor [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) were annealed using solvent vapors with either a high solubility for the donor (tetrahydrofuran), the acceptor (carbon disulfide) or both (chloroform). The samples were analyzed by grazing-incidence wide-angle X-ray scattering (GIWAXS), electron diffraction, X-ray pole figures, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). A phase separation of DRCN5T and PC71BM is induced by SVA leading to a crystallization of DRCN5T and the formation of a DRCN5T enriched layer. The DRCN5T crystallites possess the two dimensional oblique crystal system with the lattice parameters a = 19.2 Å, c = 27.1 Å, and β = 111.1° for the chloroform case. No major differences in the crystal structure for the other solvent vapors were observed. However, the solvent choice strongly influences the size of the DRCN5T enriched layer. Missing periodicity in the [010]-direction leads to the extinction of all Bragg reflections with k ≠ 0. The annealed samples are randomly orientated with respect to the normal of the substrate (fiber texture).

Fully Solution Processed, Stable, and Flexible Bifacial Polymer Solar Cells

Photon capturing is an essential step for the operation of a solar cell. In this article, we develop a bifacial solar cell with characteristics of double-side photon collection, transparent appearance, mechanical flexibility, and facile processing. The whole device was fully fabricated by a spin-coating technique. A power conversion efficiency (PCE) as high as 2.46% has been achieved using the most prominent photoactive material, poly(3-hexylthiophene):(6, 6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM). The bifacial solar cell can retain 92% of its original PCE after 350 cyclic bending cycles at bending radii of 7.4 mm. In addition to the mechanical instability of the device, photochemical degradation is partially involved in the device operation. We believe that our device with its promising mechanical, physical, and processing features can serve as an essential power element to be integrated with other technologies for the next-generation self-powered technology.

Multistage Resistive Switching Processes in Filament Conduction-Based Organic Memory Devices

The broken processes of carbon-rich conducting filament have been clarified in composite of [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) and poly(4-vinyl phenol) (PVP) based resistive memory devices. Here, the multistage resistive switching processes in Al/PCBM + PVP/Al sandwich construction were reported, which exhibits a typical nonvolatile WORM storage effect, and these several states are well separated by a resistance ratio of 1: (5.01 × 101): (2.08 × 102): (5.45 × 102): (2.42 × 103). The Al/PCBM + PVP/Al memory devices feature multistate data storage, long retention time (1 × 105 s), and large memory window (maximum ON/OFF ratio, ∼104). Furthermore, conductance quantization during resistive switching processes was analyzed. This work might promote and improve the understanding and awareness of resistive switching mechanism for organic-based memory devices.

Metallophthalocyanines in a ternary photoactive layer (P3HT:MPc:PC70BM) for bulk heterojunction solar cells

Novel bulk heterojunction organic photovoltaic solar cells have been fabricated by introducing a series of metallophthalocyanines into a photoactive blend of a poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C70 butyric acid methyl ester.

Enhancement of organic solar cell performance by incorporating gold quantum dots (AuQDs) on a plasmonic grating.

The incorporation of metallic nanoobjects into devices allows to increase light harvesting, which increases the device performance. In this study, we used a combination of gold quantum dots and grating-coupled surface plasmon resonance (GCSPR) to improve the performance of organic solar cells (OSCs) with a poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) photoactive layer. Gold quantum dots with a green fluorescent color (green-AuQD) were loaded into a hole transport layer (HTL) aiming to harvest photons in the UV region and emit visible light into the neighboring photoactive layer. Meanwhile, plasmonic grating structures, which were created on the photoactive layer surfaces via the nanoimprinting technique, provided an enhancement effect through light scattering and GCSPR. Thus, an excellent enhancement of OSC efficiency with a significant increase in short circuit photocurrent (JSC) and power conversion efficiency (PCE) in comparison to that of the reference cell was achieved. The fabricated device provides a JSC value as high as 8.41 mA cm−2 (a 14.11% enhancement) and a PCE value of 3.91% (a 19.57% enhancement). The systematic study clearly reveals that the remarkable enhancement of OSC efficiency is achieved by incorporating both AuQD and plasmonic grating.

Comparative analysis between numerical simulation of PPV/PCBM and InGaN based solar cells

Solar cells are promising renewable and without carbon electric energy asset to address the non-renewable energy source and fissile fuel shortage. Indium Gallium Nitride (InGaN thin films are now a day’s attracting researchers because of its possible use as an active semiconductor material and its immense application potential in short wavelength optoelectronic solar cells. InGaN also exhibits attractive photovoltaic (optical and electrical) properties. In this paper we had a Comparative Analysis between Numerical simulation of organic and inorganic solar cell. We have chosen Indium Gallium Nitride (InGaN) and PPV/PCBM-based solar cells. In our work we are going to find out optimization points for both of the solar cells. The characteristics of PV figures of merits of PPV solar cells simulated with the composition of polymer [6.6]-phenyl C61 butyric acid methyl ester (PCBM) to demonstrate maximum efficiency. Comparative analysis of both organic and inorganic solar cells demonstrates their pros and cons as organic solar cells are coming with good economy but low efficiency. If we are looking towards Inorganic solar cells they are having good efficiency but economically Costlier.

Elimination of Light-Soaking Effect in Hysteresis-Free Perovskite Solar Cells by Interfacial Modification

The hysteresis and light-soaking effect have been observed in organo–metal halide perovskite solar cells (PSCs) under operating conditions, which inhibit the precise evaluation of power output. The mechanisms leading to these effects are little understood. Here, our studies have demonstrated that the light-soaking effect is related to the electron selective layer/perovskite interface in hysteresis-free PSCs. The introduction of [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) doped with CH3NH3I molecules as the interfacial layer can effectively release or eliminate this effect due to the efficient charge transfer, accompanied with the best stable output efficiency of 19% and an ultrahigh fill factor over 84%. Capacitance–voltage and capacitance–frequency curves derived from electrochemical impedance spectroscopy demonstrate that the light-soaking effect in PSCs mainly originates from the charge accumulation at the PC61BM/perovskite interface. The CH3NH3I doped in PC61BM forestalls the ion movement amon...

Enhancing the power conversion efficiency of organic solar cells

Organic solar cells (OSCs) have significantly reduced the overall cost of solar energy system, making solar oriented devices universally clean and green energy source. However, to make OSCs more competitive in diverse photovoltaic (PV) technologies, it is essential to attain high efficiencies by analyzing novel materials and realizing optimal arrangements of donor–acceptor materials. In this paper, we attempt to show a terse depth insight of OSCs by investigating three novel architecture schemes with special emphasis on improving the power conversion efficiency. The materials include include i) poly (3-hexylthiophene):[(6,6)]-phenyl C61 butyric acid methyl ester (P3HT:PCBM), ii) thieno [3,4-b] thiophene-alt-benzodithiophene [6,6]:-phenyl-C61 butyric acid methyl ester (PTB7:PCBM), and iii) poly{4,4′-bis(2-ethylhexyl) dithieno [3,2-b:2′,3′-d] silole-alt-5,6-difluoro-4,7-bis (4-hexylthiophen-2-yl)-2,1,3-benzothiadiazle): [6,6]-phenyl-C61 butyric acid methyl ester (PDTS-DTffBT:PCBM), respectively. Results show that the extracted performance parameters including short circuit current (JSC) = 10.88 mA/m2, open circuit voltage (Voc) = 0.82 V, fill factor (FF) = 83.52 %, and efficiency (ƞ) = 7.49 % is highest for the second scheme among others. Different intermediate layers have also been analyzed with the objective to reduce the recombination losses and enhance the power conversion efficiency of the proposed cell. The impact of temperature on the overall ղ is also presented and it is discovered that high temperature reduces the performance of the solar cell. Furthermore, the performance of the proposed structure is compared with various kinds of OSCs and it is found that our design exhibit highest efficiency. The achievement of high efficiencies in this work may accelerate the practical applications of OSCs.

Interface engineering with a novel n-type small organic molecule for efficient inverted perovskite solar cells

Abstract Fullerene derivatives are promising electron transporting materials for low-temperature processed inverted perovskite solar cells (PSCs). However, fullerene derivatives have some disadvantages, e.g. [6,6]-phenyl C61 butyric acid methyl ester (PCBM) has unmanageable morphology, low electron mobility and easily generated non-radiative recombination, which restrict the performance of PSCs. Herein, a novel n-type small organic molecule, homologous perylene diimide tetramer (HPDT), is designed and synthesized in this work to engineer the interface properties by enhancing interface contact, decreasing energetic barrier and recombination losses. HPDT shows suitable energy levels and high electron mobility and thus will increase the electron mobility during interface engineering in the inverted PSCs. Moreover, coating HPDT on top of perovskite prior to the deposition of PCBM is helpful to achieve a homogeneous pinhole-free PCBM layer, leading to enhanced power conversion efficiency from 17.38% up to 19.75% for inverted MAPbI3 PSCs along with a negligible hysteresis. Significantly, our results undoubtedly provide new guidelines in exploring n-type organic small molecules for high-performance PSCs.

Fullerene for the Improvement of PbS QDs-Based Hybrid Solar Cells

In the present study, the hybrid photovoltaic devices based on PbS quantum dots (QDs) and poly(3-hexylthiophene-2,5diyl) have been fabricated. The effect of the insertion of [6,6]-phenyl C71 butyric acid methyl ester (PCBM) into the hybrid blend has been investigated and analyzed by using light and dark current density-voltage measurement, and impedance spectroscopy: capacitance-frequency and capacitance-voltage measurement. It is demonstrated that the introduction of PCBM into solar cells improves their efficiency with the optimal PCBM concentration of 3 wt %. It is shown that the main contribution in limitation of solar cells efficiency is brought by shallow traps induced by air exposure.

Investigation of humidity effects on electrical properties of PTB7-Th and PCBM sensor

This paper reports the fabrication of semitransparent semisurface-type samples of an indium tin oxide (ITO)/poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b 0] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}: (PTB7-Th):[6,6]-Phenyl C61 butyric acid methyl ester (PCBM)/graphene composite humidity sensor. The transparency of the sensor was 58–60%. The dependences of the resistance, impedance and capacitance at 100 Hz, 1 kHz, 10 kHz, 100 kHz and 200 kHz of the ITO/PTB7-Th:PCBM/graphene composite samples on relative humidity in the range 50–93% were investigated. It was observed that as humidity increased from 50 to 93%, the resistance and impedances (at 1 kHz) of the samples decreased on average by factors of 7·48 and 58·75, respectively. Under the same experimental conditions (1 kHz), the capacitances of the samples increased by a factor of 42. As the frequency was increased from 100 Hz to 200 kHz, the impedance decreased by factors of 20 and 7 at relative humidity values of 50 and 62%, respectively. The corresponding capacitance decreased by factors of 33 and 178, respectively. The semitransparent PTB7- and -PCBM-based humidity sensors can be used for measurement of humidity, as well as a teaching aid where control of illumination or light intensity is desirable.

RGO induced structural and microstructural properties of P3HT in the performance and stability of polymer solar cells

With recent technological advancement, interest towards energy efficient flexible devices have grown appreciably. Graphene is one of the most renowned material due to its exclusive physical properties together with ultrahigh specific surface area and high carrier mobility of ∼104 V.s. Filler modified physical properties of reduced graphene oxide (rGO)/Poly[3-hexylthiophene-2,5-diyl] (P3HT) blends with [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) have been reviewed carefully in active layer of the organic solar cells. Physio-chemical properties of rGO modified P3HT blends have been analyzed using peculiar characterization tools such as x-ray diffraction (XRD), scanning electron microscope (SEM), UV–visible (UV–vis), Fourier transform infrared, Raman and photo luminescence (PL) spectroscopic techniques along with cyclic-voltammetry measurements. Open-circuit voltage (Voc) of 0.66 V, current-density (Isc) of ∼10.6 mA cm−2 and efficiency of ∼3.71% have been ascertained for the device with 1.6 wt% of rGO in the active layer. RGO induced additional exciton dissociation sites and efficient carrier transport through the conducting rGO network in the active layer is attributed for the improved performance of the solar cells. The effect of introducing ZnO electron transport layer (ETL) on the device performance as well as the stability of the solar cell is investigated.

Hysteresis Passivation in Planar Perovskite Solar Cells Utilizing Facile Chemical Vapor Deposition Process and PCBM Interlayer

Low-cost, high-efficiency perovskite solar cells (PSCs) have the distinguished potential to be next commercialized photovoltaic devices. Chemical vapor deposition (CVD) process was regarded as an excellent choice as compared to solution deposition technique, however, the photovoltaic and stable performance of the former lags behind that of the latter. In this work, we propose a facile CVD pattern to fabricate PSCs, substrates covered by lead iodide (PbI2) sandwich-surrounded by the source methyl-ammonium iodide (CH3NH3I, MAI) powder. Heat and mass transfer, surface reactions are involved in the CVD deposition procedure. Numerical calculations present a uniform distribution of MAI vapor, contributing to homogeneous perovskite films with comparable surface morphologies, crystal structures and photovoltaic performances, despite of the notorious hysteresis. Herein, a PCBM ([6,6]-Phenyl C61 butyric acid methyl ester) interlayer is introduced before the PbI2 coating and the CVD process. Results show that even suffered from the torturous CVD procedure, the PCBM interlayer still works to passivating the bulk and interfacial recombination, reducing the hysteresis, improving the grain structure of perovskite films. Hence, the photovoltaic performance of PSCs enhances by 30%, and the filling factor difference between the forward and the reverse scan reduces to 6%.

Impact of A-D-A-Structured Dithienosilole- and Phenoxazine-Based Small Molecular Material for Bulk Heterojunction and Dopant-Free Perovskite Solar Cells.

Herein, the synthesis of the novel acceptor-donor-acceptor (A-D-A)-structured small molecule Si-PO-2CN based on dithienosilole (DTS) as building block flanked by electron-rich phenoxazine (POZ) units, which are terminated with dicyanovinylene, is presented. Si-PO-2CN showed unique electrochemical and photophysical properties and has been successfully employed in perovskite solar cells (PSCs) as well as in bulk heterojunction organic solar cells (OSCs). The PSCs fabricated with dopant-free Si-PO-2CN as hole-transport material (HTM) exhibited a power conversion efficiency (PCE) of 14.1 % (active area=1.02 cm2 ). Additionally, a PCE of 5.6 % has been achieved for OSCs, which employed Si-PO-2CN as p-type donor material when blended with a [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) acceptor. The versatile application of Si-PO-2CN provides a pathway for further implementation of DTS-based building blocks in solar cells for designing new molecules.

Efficient Anti-solvent-free Spin-Coated and Printed Sn-Perovskite Solar Cells with Crystal-Based Precursor Solutions

Summary Tin-based perovskite solar cells (PSCs), with more consummate optical band gaps, lower exciton-binding energies, and higher charge-carrier mobility, have not attracted tremendous research efforts compared with the lead-based ones that have a record power conversion efficiency (PCE) of 24.2%. The major challenges for Sn-based research are significantly low open-circuit voltage, poor reproducibility, and environmental instability. It has been identified that the oxidation processes take place during the preparation of precursor solutions and fabrication of films, due to the low redox potential of the stannous absorption layer. Herein, we propose two strategies of crystal-resolving and recrystallization technology to reduce the oxidation process. As a result, PCEs of 8.9% (active area of 0.04 cm2) and 5.5% (active area = 1.01 cm2) are attained using the inverted p-i-n structure, which will lead to a revival of lead-free PSC research.

Metal-electrode-free inverted organic photovoltaics using electrospray-deposited PEDOT:PSS and spin-coated HAT-CN exciton blocking layer

Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) films were fabricated using an electrospray deposition (ESD) method. The ESD PEDOT:PSS films exhibited higher PSS content on the surface than spin-coated PEDOT:PSS films, which results in a higher work function. Based on this result, metal-electrode-free inverted organic photovoltaics (OPVs) were fabricated. The ESD PEDOT:PSS was used as the top electrode on the poly(3-hexythiophene-2,5-diyl) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM) light-absorbing layer. The power conversion efficiency (PCE) of OPVs was significantly increased with the 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile layer. The improved PCE would be attributed to the suppression of exciton quenching at the P3HT:PCBM and PEDOT:PSS interface.

Solution processed CuSCN/perylene hole extraction layer for highly efficient and stable organic solar cells

In this work, we report a solution processed hole extraction layer (HEL) for highly efficient organic solar cells (OSCs), which is formed by CuSCN and perylene. It shows that the introduction of perylene helps to polish the interface between HEL and active layers, leading to efficient charge transport and collection, diminished recombination loss, and thereby improving the photovoltaic performance. In poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b; 4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]:[6,6]-phenyl C71-butyric acid methyl ester (PTB7-Th:PC71BM) based OSCs, over 9% enhancement of power conversion efficiency (PCE) is obtained in the cells using bilayer CuSCN/perylene as HEL compared with that of the reference cell using pure CuSCN as HEL. The advantage of bilayer CuSCN/perylene HEL is also confirmed in nonfullerene system. An improved PCE is also obtained after application of perylene in nonfullerene system based cell. Furthermore, superior air stability has been observed in CuSCN and CuSCN/perylene HEL based cells. The use of a bilayer CuSCN/perylene HEL proves a potential approach to obtain efficient and stable OSCs.

Enhanced UV–visible detection of InGaZnO phototransistors via CsPbBr3 quantum dots

Indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) exhibit high field-effect carrier mobility and low off-state current, which are attractive for high speed and low noise photodetectors and image sensor applications. However, with an optical band gap of ∼3.3 eV, the photodetection range of IGZO TFTs is limited to short wavelength ultraviolet (UV) light. Here, we demonstrate a simple approach to enhance the performance of IGZO-based phototransistors by incorporating layers of solution-processed perovskite quantum dots (QDs) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Owing to the fast transfer of photogenerated electrons by CsPbBr3 QDs absorbing layer, the photoresponse of QD-decorated IGZO phototransistor is extended to the visible range (500 nm), and the responsivity and detectivity of QD-decorated device are more than two order higher than those of original IGZO TFTs. Moreover, the QD-decorated IGZO phototransistor also exhibits enhanced performance under UV light (350 nm), achieving a responsivity of 9.72 A W−1, a detectivity of 2.96 × 1012 Jones, and a light to dark current ratio in the order of 106 at a wavelength of 350 nm (a light intensity of 207.3 μW cm−2).