Modeling the Effect of Annealing and Regioregularity on Electron and Hole Transport Characteristics of Bulk Heterojunction Organic Photovoltaic Devices

2010 ◽  
Vol 1270 ◽  
Author(s):  
Shabnam Shambayati ◽  
Bobak Gholamkhass ◽  
Soheil Ebadian ◽  
Steven Holdcroft ◽  
Peyman Servati
Keyword(s):  
Annealing Time ◽  
Electron Mobility ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Hole Mobility ◽  
Phase Segregation ◽  
Hole Transport ◽  
Trap States ◽  
Current Voltage ◽  
Steep Decline

AbstractIn this study, the dark current-voltage characteristics of electron-only and hole-only poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) as a function of regioregularity (RR) and annealing time is investigated using the mobility edge (ME) model. This model is used to analyze the degradation of electron and hole mobilities as a function of annealing time for 93%-RR and 98%-RR P3HT:PCBM devices. The hole mobility is almost unchanged by the RR nature of P3HT and thermal annealing. The electron mobility, however, behaves differently after annealing. The electron mobility of 98%-RR devices, which is initially higher than that of the 93%-RR devices, experiences a steep decline with annealing. Based on ME analysis, this is due to an increase in trap states in the exponential tail caused by phase segregation of solid state blends of 98%-RR polymer and PCBM. The electron mobility of 93%-RR devices increases with annealing due to an optimization of nano-phase separated morphology.

scholarly journals Светоизлучающие полевые транзисторы на основе композитных пленок полифлуорена и нанокристаллов CsPbBr-=SUB=-3-=/SUB=-

2019 ◽  
Vol 61 (2) ◽  
pp. 388
Author(s):  
А.Н. Алешин ◽  
И.П. Щербаков ◽  
Д.А. Кириленко ◽  
Л.Б. Матюшкин ◽  
В.А. Мошников
Keyword(s):  
Field Effect Transistors ◽  
Composite Films ◽  
Hole Mobility ◽  
Hole Transport ◽  
Component Ratio ◽  
Organic Field Effect Transistors ◽  
Electrical And Optical Properties ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Voltage Characteristics

Abstract—Light-emitting organic field-effect transistors (LE-FETs) on the basis of composite films that consist of perovskite nanocrystals (CsPbBr_3) embedded in a matrix of conjugated polymer—polyfluorene (PFO)—have been obtained, and their electrical and optical properties have been investigated. Output and transfer current-voltage characteristics (I-Vs) of FETs based on PFO : CsPbBr_3 films (component ratio 1 : 1) have a slight hysteresis at temperatures of 100–300 K and are characteristic of hole transport. The hole mobility is ∼3.3 and ∼1.9 cm^2/(V s) at the modes of the saturation and low fields, respectively, at 250 K and reaches ∼5 cm^2/(V s) at 100 K. It has been shown that the application of pulsed voltage to LE-FETs based on PFO : CsPbBr_3 can reduce the ionic conductivity and provide electroluminescence in this structure at 300 K.

3× 1018 - 1 × 1019 cm -3 Al+ Ion Implanted 4H-SiC: Annealing Time Effect

2020 ◽  
Vol 1004 ◽  
pp. 683-688
Author(s):  
Roberta Nipoti ◽  
Antonella Parisini ◽  
Virginia Boldrini ◽  
Salvatore Vantaggio ◽  
Mariaconcetta Canino ◽  
...  
Keyword(s):  
Annealing Time ◽  
Carrier Transport ◽  
Annealing Temperature ◽  
Hole Mobility ◽  
Hole Density ◽  
Fitting Procedure ◽  
Current Voltage ◽  
Hall Effect Measurements ◽  
Extended States ◽  
Post Implantation

This work takes into account low Al implanted concentrations of 3 x 1018 cm-3 and 1 x 1019 cm-3 to compare the results of 1600°C and 1950°C post-implantation annealing treatments, done with two different annealing times per given implanted Al concentration and post implantation annealing temperature. Current-voltage and Hall effect measurements were performed to have the drift hole density and the drift hole mobility curves in the temperature range 100 - 650 K. The fitting of these curves in the frame of a carrier transport into the extended states of the valence band were performed to estimate the Al acceptor density, the donor compensator density, and the Al acceptor ionization energy. Peculiar feature of hole density and hole mobility curves is a contemporaneous increase of both carrier density and mobility values with increasing annealing time, which is congruent with the output parameters of the fitting procedure. The latter shows an almost stable Al electrical activation and a decrease of compensation with increasing annealing time for constant annealing temperature and given implanted Al concentration.

Hole injection and transport in a fluorene-containing copolymer

2002 ◽  
Vol 734 ◽  
Author(s):  
Rizwan U. A. Khan ◽  
Theo Kreouzis ◽  
Dmytro Poplavskyy ◽  
Donal D. C. Bradley
Keyword(s):  
State Of The Art ◽  
Time Of Flight ◽  
Hole Mobility ◽  
Hole Transport ◽  
Hole Injection ◽  
Space Charge Limited Current ◽  
Polymer Leds ◽  
Current Voltage ◽  
Transport Site ◽  
Polystyrene Sulphonate

ABSTRACTWe have studied the electrical properties of a fluorene-containing copolymer which is currently being developed for state-of-the-art blue polymer LEDs. This copolymer is made up of three functional groups which are nominally the hole-conducting, electron conducting and emissive regions. Using a combination of current/voltage, time-of-flight and dark injection transient versus temperature measurements, the injection and transport properties of the material have been investigated. Hole injection from polystyrene sulphonate doped polyethylenedioxythiophene (PEDOT:PSS) into the polymer is found to be consistent with an ohmic contact. Hole transport within the fluorene copolymer is found to possess a mobility that is two orders of magnitude lower than that for previously studied polymers containing the copolymer constituents. Using the equations for trap-free space-charge limited current, predicted J/V characteristics have been obtained from the mobility values derived using the time-of-flight technique. We discuss both the reduced hole mobility of the copolymer, and the discrepancies between the measured and predicted J/V characteristics, in terms of variations in both the trap and transport site densities and their energetic and spatial distributions.

Variation of the Photocurrent Spectra due to Energy Dependent Hole Mobility in Organic Bulk Hetero-junction Solar Cells

2012 ◽  
Vol 1435 ◽  
Author(s):  
Buddika K. Abeyweera ◽  
Bruce W. Alphenaar
Keyword(s):  
Solar Cells ◽  
Absorption Maximum ◽  
Bulk Heterojunction ◽  
Hole Mobility ◽  
Hole Transport ◽  
Low Energy ◽  
Energy Response ◽  
Heterojunction Solar Cells ◽  
Cell Efficiency ◽  
Photocurrent Spectra

ABSTRACTA comparison of the photocurrent spectra of organic bulk heterojunction solar cells of various thicknesses is presented. Increasing the thickness of the active layer in both MDMO-PPV /PCBM and P3HT/PCBM solar cells reduces the magnitude of the photocurrent due to the low mobility of the photogenerated holes. Measurements show that the photocurrent reduction is predominately due to a loss in carriers generated at the polymer absorption maximum, while the low energy response is relatively unaffected. In a thick enough sample, the low energy response (1.5-2 eV) dominates, and a photocurrent peak is no longer observed at the main absorption maximum (2.6 eV). The results imply that hole transport is blocked for carriers generated in the polymer at higher energy. Because these holes are generated at the absorption maximum their low mobility could be a major factor limiting solar cell efficiency.

Effect of carbon nanotube incorporation into polythiophene-fullerene-based organic solar cells

2014 ◽  
Vol 92 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Kirill Skupov ◽  
Alex Adronov
Keyword(s):  
Carbon Nanotube ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Grazing Incidence ◽  
Hole Transport ◽  
Full Length ◽  
Knowing That ◽  
Device Efficiency ◽  
Hole Transporting

The effect of single-walled carbon nanotube (SWNT) incorporation within bulk heterojunction photovoltaic devices based on poly(3-hexylthiophene) − [6,6]-phenyl-C61-butyric acid methyl ester (P3HT−PCBM) (1:1 w/w) active layers was investigated. Both full-length and shortened SWNTs were introduced within the P3HT−PCBM layer at loadings in the range of 0−2 wt%. For full-length SWNTs, it was found that device efficiency decreased at all SWNT loading levels and annealing temperatures, which ranged from 80 to 225 °C. The highest average external efficiencies in the absence of SWNTs reached approximately 2%, while the best efficiencies in devices incorporating the full-length SWNTs only reached 1.3%. When shortened SWNTs were incorporated, device efficiency was unchanged upon annealing at 160 °C (average values of approximately 2%), but the efficiency improved by nearly 50%, relative to controls when devices were annealed at 70 °C. Active layer analysis by grazing incidence X-ray diffraction indicated that nanotubes did not increase polymer crystallinity. Knowing that shortened SWNTs are good hole conductors, it is postulated that the improved device efficiency is due to improved hole transport through the SWNTs in devices where the hole-transporting polymer has not been allowed to adopt its optimal morphology due to underannealing.

scholarly journals Solution-Processed Bulk Heterojunction Solar Cells with Silyl End-Capped Sexithiophene

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Jung Hei Choi ◽  
Mohamed E. El-Khouly ◽  
Taehee Kim ◽  
Youn-Su Kim ◽  
Ung Chan Yoon ◽  
...  
Keyword(s):  
Bulk Heterojunction ◽  
Short Circuit ◽  
Acid Methyl Ester ◽  
Hole Mobility ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
Solution Processed ◽  
Heterojunction Solar Cells

We fabricated solution-processed organic photovoltaic cells (OPVs) using substituted two sexithiophenes, a,w-bis(dimethyl-n-octylsilyl)sexithiophene (DSi-6T) and a,w-dihexylsexithiophene (DH-6T), as electron donors, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor. Solution-processed OPVs usingDH-6TandDSi-6Tshowed good photovoltaic properties in spite of their poor solubility. The best performance was observed onDSi-6T : PCBM 1 : 5 (w/w) blend cell with an open circuit voltage (Voc) of 0.63 V, short circuit current density (Jsc) of 1.34 mA/cm2, fill factor (FF) of 55%, and power conversion efficiency of 0.44% under AM 1.5 G illumination. AlthoughDH-6Thas higher hole mobility thanDSi-6T, theDSi-6T : PCBM blend cell showed higher hole mobility thanDH-6T : PCBM cell. Therefore,DSi-6Tcell showed higher device performance thanDH-6Tcell due to its silyl substitutions, which lead to the increase of the solubility. The incorporation of solution-processed TiO2interfacial layer in theDSi-6T : PCBM devices significantly enhances FF due to the reduced charge recombination near active layer/Al interface.

Electron and hole transport in solution-processed fullerenes

2021 ◽  
Author(s):  
Gert-Jan A. H. Wetzelaer ◽  
Paul W. M. Blom
Keyword(s):  
Solar Cells ◽  
Methyl Ester ◽  
Charge Transport ◽  
Transport Properties ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Hole Transport ◽  
Heterojunction Solar Cells ◽  
Acid Methyl ◽  
Butyric Acid Methyl Ester

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.

Packing Effect on the Transfer Integrals and Mobility in α,α′-bis(dithieno[3,2-b:2′,3′-d]thiophene) (BDT) and its Heteroatom-Substituted Analogues

2011 ◽  
Vol 64 (12) ◽  
pp. 1587 ◽  
Author(s):  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Shabbir Muhammad ◽  
Jingping Zhang
Keyword(s):  
Electron Transfer ◽  
Electron Mobility ◽  
Hole Mobility ◽  
Experimental Investigations ◽  
Hole Transfer ◽  
Space Group ◽  
Space Groups ◽  
Transfer Integrals ◽  
Packing Effect ◽  
Good Agreement

Theoretically calculated mobility has revealed that BDT is a hole transfer material, which is in good agreement with experimental investigations. The BDT, NHBDT, and OBDT are predicted to be hole transfer materials in the C2/c space group. Comparatively, hole mobility of BHBDT is 7 times while electron mobility is 20 times higher than the BDT. The packing effect for BDT and designed crystals was investigated by various space groups. Generally, mobility increases in BDT and its analogues by changing the packing from space group C2/c to space groups P1 or . In the designed ambipolar material, BHBDT hole mobility has been predicted 0.774 and 3.460 cm2 Vs–1 in space groups P1 and , which is 10 times and 48 times higher than BDT (0.075 and 0.072 cm2 Vs–1 in space groups P1 and ), respectively. Moreover, the BDT behaves as an electron transfer material by changing the packing from the C2/c space group to P1 and .

scholarly journals Pseudo-Planar Organic Heterojunctions by Sequential Printing of Quasi-Miscible Inks

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 586
Author(s):  
Ana-Gianina Gereanu ◽  
Camillo Sartorio ◽  
Aurelio Bonasera ◽  
Giuliana Giuliano ◽  
Sebastiano Cataldo ◽  
...  
Keyword(s):  
Inkjet Printing ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Bond Number ◽  
Molecular Organization ◽  
Low Viscosity ◽  
Donor Acceptor ◽  
Interfacial Mixing ◽  
Planar Heterojunction

This work deals with the interfacial mixing mechanism of picoliter (pL)-scale droplets produced by sequential inkjet printing of organic-based inks onto ITO/PET surfaces at a moderately high Weber number (~101). Differently from solution dispensing processes at a high Bond number such as spin coating, the deposition by inkjet printing is strictly controlled by droplet velocity, ink viscosity, and surface tension. In particular, this study considers the interfacial mixing of droplets containing the most investigated donor/acceptor couple for organic solar cells, i.e., poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM), showing how low-viscosity and low-surface energy inks can be leveraged for the fabrication of an interface suitable for a pseudo-planar heterojunction (pseudo-PHJ) organic solar cell (OSC) that is a convenient alternative to a bulk heterojunction (BHJ) OSC. The resulting thin-film morphology and molecular organization at the P3HT/PCBM interface are investigated, highlighting the roles of dissolution-driven molecular recirculation. This report represents a first step toward the sequential inkjet printing fabrication of pseudo-PHJ OSCs at low consumption of solvents/chemicals.

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