Dynamics of Charge Transfer Excitons Recombination in Polymer/Fullerene Solar Cells

2011 ◽  
Vol 1286 ◽  
Author(s):  
Markus Hallermann ◽  
Felix Deschler ◽  
Josef Berger ◽  
Elizabeth von Hauff ◽  
Enrico Da Como
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Power Law ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Strong Dependence ◽  
Acid Methyl Ester ◽  
Open Circuit ◽  
Fullerene Derivative ◽  
Charge Transfer Excitons

ABSTRACTAmong the different recombination mechanisms in organic solar cells the photoluminescence (PL) of charge transfer excitons (CTEs) has been identified has one of the most important, impacting both the open circuit voltage and the short circuit current. Here, we study their recombination dynamics, monitoring the decay of the PL on a time scale spanning three orders of magnitude from nanoseconds to microseconds. As a model system we investigate blends of the conjugated polymer poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene-vinylene) (MDMO-PPV) and the fullerene derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM). We observe that the dynamics of recombination follows a power-law, which is independent of sample morphology. Upon application of a transient electric field, which is capable of separating the bound charge pairs, we observe different dynamics of recombination only for the separated pairs. Those also follow a power-law and show a strong dependence on the film morphology.

Nanoscale Phase Separation in Ternary Organic Solar Cells Based on PTB7:PC70BM:IC70BA

2021 ◽  
Vol 21 (11) ◽  
pp. 5749-5755
Author(s):  
Chang Li ◽  
Wei Li ◽  
Xiaoxiang Sun ◽  
Jifei Wang ◽  
Jiayou Tao ◽  
...  
Keyword(s):  
Solar Cells ◽  
Phase Separation ◽  
Active Layer ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Weight Ratio ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Hole Transport ◽  
Fullerene Derivative

As a fullerene derivative, IC70BA is widely used in the ternary organic solar cells (TOSCs) to increase the open circuit voltage (Voc) of the devices. Unfortunately, most of the literature shows that IC70BA will lead to a reduction in the short-circuit current density (Jsc) and fill factor (FF). In this work, IC70BA is added to the PTB7:PC70BM binary system to form the ternary system, which is composed of one donor and two fullerene acceptors. Surprisingly, the addition of IC70BA does not immediately lead to a decrease in Jsc and FF. In fact, the appropriate weight ratio of IC70BA in fullerenes can simultaneously increase the Voc, Jsc, and FF of the TOSCs. The synergistic optimization of the surface and bulk morphology of the ternary active layer suppresses the attenuation of Jsc and FF. The smooth surface and suitable phase separation size effectively guarantee the separation, transport and extraction of the charge. Moreover, the addition of IC70BA can significantly improve the hole transport capacity of the active layer, and the optimal hole mobility is 5.13 – 10”4 cm2V–1S–1. Finally, the TOSCs with 10% weight ratio of IC70BA gives the optimal PCE of 9.24% and ideality factor of 2.3.

scholarly journals SCAPS Simulation on P3HT:Graphene Nanocomposites Based Bulk-Heterojunction Organic Solar Cells

2019 ◽  
Vol 9 (1) ◽  
pp. 28
Author(s):  
Nur Shakina Mohd Shariff ◽  
Puteri Sarah Mohamad Saad ◽  
Mohamad Rusop Mahmood
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Fill Factor ◽  
Bulk Heterojunction ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Simulation Software ◽  
Capacitance Voltage

There has been an increasing interest towards organic solar cells after the discovery of conjugated polymer and bulk-heterojunction concept. Eventhough organic solar cells are less expensive than inorganic solar cells but the power conversion energy is still considered low. The main objective of this research is to investigate the effect of the P3HT’s thickness and concentration towards the efficiency of the P3HT:Graphene solar cells. A simulation software that is specialize for photovoltaic called SCAPS is used in this research to simulate the effect on the solar cells. The solar cell’s structure will be drawn inside the simulation and the parameters for each layers is inserted. The result such as the open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), efficiency (η), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristic will be calculated by the software and all the results will be put into one graph.

Effect of temperature on organic Schottky barrier cells

1981 ◽  
Vol 59 (6) ◽  
pp. 727-732 ◽  
Author(s):  
Rafik O. Loutfy ◽  
Cheng-Kuo Hsiao
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Schottky Barrier ◽  
Conversion Efficiency ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Power Conversion ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Photovoltaic Properties

The effect of temperature on the photovoltaic properties of indium/metal-free phthalocyanine Schottky barrier solar cells was investigated in the range 260–350 K. In general, the short circuit photocurrent, Jsc, and fill factor, ff, increased with increasing temperature (in contrast to inorganic photocells). The device series resistance and open circuit photovoltage, Voc, decreased (similar to inorganic photocells) as temperature was raised. An increase in the overall power conversion efficiency, η, has been observed with increase of temperature. In the case of x-H2Pc, the power conversion efficiency increased by 2.5 times due to a temperature rise of 60 °C above ambient. Thus, for operation at temperatures above ambient, organic solar cells may offer a significant advantage over inorganic cells.Analysis of the variation of the photovoltage with temperature showed that the decrease in Voc is mainly due to variation injunction impedance, which is controlled by thermionic current at high temperature and ionized impurity at low temperature.

scholarly journals Benzothiadiazole Based Cascade Material to Boost the Performance of Inverted Ternary Organic Solar Cells

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 450 ◽  
Author(s):  
Miron Krassas ◽  
Christos Polyzoidis ◽  
Pavlos Tzourmpakis ◽  
Dimitriοs M. Kosmidis ◽  
George Viskadouros ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Fused Ring ◽  
Electron Cascade ◽  
First Time

A conjugated, ladder-type multi-fused ring 4,7-dithienbenzothiadiazole:thiophene derivative, named as compound ‘T’, was for the first time incorporated, within the PTB7:PC71BM photoactive layer for inverted ternary organic solar cells (TOSCs) realization. The effective energy level offset caused by compound T between the polymeric donor and fullerene acceptor materials, as well as its resulting potential as electron cascade material contribute to an enhanced exciton dissociation, electron transfer facilitator and thus improved overall photovoltaic performance. The engineering optimization of the inverted TOSC, ITO/PFN/PTB7:Compound T(5% v/v):PC71BM/MoO3/Al, resulted in an overall power conversion efficiency (PCE) of 8.34%, with a short-circuit current density (Jsc) of 16.75 mA cm−2, open-circuit voltage (Voc) of 0.74 V and a fill factor (FF) of 68.1%, under AM1.5G illumination. This photovoltaic performance was improved by approximately 12% with respect to the control binary device.

Efficiency Enhancement in Organic Solar Cells by Use of Cobalt Phthalocyanine (CoPc) Thin Films

2020 ◽  
Vol 20 (6) ◽  
pp. 3703-3709 ◽  
Author(s):  
S. S. Rawat ◽  
Ashish Kumar ◽  
R. Srivastava ◽  
C. K. Suman
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Energy Level ◽  
Buffer Layer ◽  
Organic Solar Cells ◽  
Fill Factor ◽  
Series Resistance ◽  
Short Circuit ◽  
Acid Methyl Ester ◽  
Cobalt Phthalocyanine

Cobalt phthalocyanine (CoPc) nano thin films have been introduced as a hole buffer layer in organic solar cells with active layer of Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The surface morphology and opto-electrical properties of the CoPc thin films have made it an applicable materials for organic solar cells. The nano-thin films of CoPc are continuously distributed over the studied area and the roughness are around 5 to 7 nm for all thickness. The dominant optical absorptions are in the visible range of wavelengths 500 to 800 nm. The CoPc buffer layer is suitable for energy level matching in energy level diagram and enhances the absorption spectrum as well, which facilitate the charge carrier generation, increases charge transport, decreases charge recombination, hence enhance the all device parameters short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF). The solar cells efficiency increases by ˜70% and the fill factor increases by ˜45% in comparison to the standard cells. The increase in efficiency and the fill factors of the solar cells may also be attributed to the increasing of shunt and lowering the series resistance of the cells. The cole–cole plots of the devices may be modeled in electrical circuit as a single parallel resistance Rb and capacitance Cb network with a series resistance Rc.

scholarly journals Short circuit current improvement in planar heterojunction organic solar cells by multijunction charge transfer

2012 ◽  
Vol 100 (5) ◽  
pp. 053301 ◽  
Author(s):  
J. C. Wang ◽  
S. Q. Shi ◽  
C. W. Leung ◽  
S. P. Lau ◽  
K. Y. Wong ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Planar Heterojunction

RELIABILITY STUDIES OF P3HT: PCBM ORGANIC SOLAR CELLS FABRICATED WITH CALCIUM–ALUMINUM AND LITHIUM FLUORIDE–ALUMINIUM CATHODES

2011 ◽  
Vol 10 (04n05) ◽  
pp. 803-807
Author(s):  
T. S. KRISHNAN ◽  
S. SUNDAR KUMAR IYER
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Continuous Illumination ◽  
Stress Tests ◽  
Ambient Conditions ◽  
Over Time

This work addresses the shelf life characteristics of P3HT: PCBM blend based organic solar cells (OSC) fabricated with Ca–Al and LiF–Al cathodes. Some of these devices are encapsulated in nitrogen ambient and some in room ambient. Device electrical characteristics are studied under both dark and light. In the analysis under dark ambient conditions, the degradation in peak dark current is monitored over time (in days) and an empirical model is postulated for the degradation based on statistical curve fitting techniques. In the analysis under light, degradation of parameters such as fill factor (FF), open circuit voltage (V oc ) and short circuit current density (J sc ) is monitored over time in these devices (for different cathodes and different ambients) and the results are analyzed and compared. Also, accelerated stress tests are conducted wherein the devices are subjected to continuous illumination for a period of 1.5 h under two different intensities (0.76 sun and 1 sun) and again, the results are analyzed and compared. A model is fitted to the observed degradation in normalized J sc and the degradation constants (k deg ) are obtained. It is seen that the devices fabricated with cathode as LiF–Al and being encapsulated in nitrogen ambient provide the best performance over time.

Design and characteration of planar star-shaped oligomer electron donors for organic solar cells: a DFT study

2015 ◽  
Vol 93 (11) ◽  
pp. 1181-1190 ◽  
Author(s):  
Dongmei Wang ◽  
Zhiyuan Geng
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Charge Transfer ◽  
Energy Level ◽  
Organic Solar Cells ◽  
Density Functional ◽  
Short Circuit ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Functional Theory

To seek high-performance oligomer donor materials used in organic solar cells, four star-shaped molecules with a planar donor core derived from the recent reported molecule 3T-P-DPP (phenyl-1,3,5-trithienyl-diketopyrrolopyrrole) were designed. The molecular properties affecting the cell performance, such as structural characteristics, frontier molecular orbital energy level, absorption spectra, exciton character, and charge transfer/transport, were investigated by means of the density functional theory and time-dependent density functional theory methods. Comparative analysis showed that the new designed molecule 3 with a TTT (2,4,6-tri(thiophen-2-yl)-1,3,5-triazine) core has better planarity, a lower HOMO energy level, and a higher absorption efficiency, as well as more favorable exciton dissociation and charge transfer than the others, potentially improving the open-circuit voltage and short-circuit current density. Consequently, 3 maybe superior to 3T-P-DPP and may act as a promising donor material candidate for organic solar cells.

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