CN1286188C - Photo sensitive thin film for polymer photovoltaic cells and method for making same - Google Patents

Abstract

The present invention relates to a photoconductive film for a polymer photovoltaic cell. The main body of the present invention comprises a composite film which is rotationally coated on conductive glass after poly 2-methoxyl-5-(p-hexyl) methyl-1, 4-p-phenyl vinylene and C60 are mixed according to a weight ratio of 1: 1 or 1: 2, and salt of which the weight is 1 to 5 wt% of that of the 2-methoxyl-5-(p-hexyl) methyl-1 and 4-p-phenyl vinylene is added. The salt comprises metal salt, organic ammonium salt and imidazole ionic liquid salt. The short circuit current and the energy conversion efficiency of a photovoltaic cell can be obviously enhanced through adding the salt with certain thickness in the 2-methoxyl-5-(p-hexyl) methyl-1 and the 4-p-phenyl vinylene/ the C60 when the photoconductive film is applied to the photovoltaic cell. The present invention also relates to a preparation method and the application of the photoconductive film in a solar cell.

Description

A kind of photo-conductive film that is used for the polymer photovoltaic cell and preparation method thereof

Technical field

The present invention relates to a kind of photo-conductive film, particularly relate to a kind of photo-conductive film that is used for the polymer photovoltaic cell, its main body is the poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1 that is spin-coated on the electro-conductive glass, 4-supports styrene) (for simplicity, hereinafter all abbreviating MEH-PPV as)/C ₆₀Laminated film, and in MEH-PPV, added the salt of the 1-5wt% of MEH-PPV weight.

Background technology

In recent years, owing to recognize the non-renewable of fossil energy and because of its use causes pollution to environment, people more and more pay attention to this cleaning of solar energy, the rational and efficient use of regenerative resource.Solar cell is to be a kind of device of electric energy with conversion of solar energy, also is the effective method of manually utilizing solar energy at present.Present commercial solar cell mostly is the inorganic material preparation, as: silicon (Si), copper indium diselenide (CuInSe), cadmium telluride (CdTe), GaAs (GaAs) etc.Its manufacture craft comparative maturity, energy conversion efficiency have reached theoretical boundary substantially.Inorganic solar cell is to material, and preparation technology etc. require very high, and energy consumption is big, thereby cost is very high.Polymer solar battery compares with it that to have preparation technology simple, cost is low, can be made into the large area flexible device, can modify the electrical conductance of adjusting material by doping or chemical molecular, advantages such as the polymer bandwidth is adjustable have caused and have paid close attention to [1:Winder C. widely; Matt G.; Hummelen J.C.; Janssen R.A.J.; SariciftciN.S.; Brabec C.J.Thin Solid Films, 2002,403:373.2:Sariciftci N.S.CurrentOpinion in Solid State and Materials Science, 1999,4:373].

The structure of existing polymer solar battery is a sandwich type, as shown in Figure 1, be followed successively by from bottom to top glass substrate, ITO conductive layer, PEDOT:PSS resilient coating (i.e. poly-(3,4-epidioxy ethylthiophene): poly styrene sulfonate), by polymer as electron donor and C ₆₀The photoactive thin film-layer of forming as electron acceptor and as the metal Ca of the vacuum evaporation of negative electrode or the electrode film of Al.Comparatively common polymer and C in the document wherein ₆₀System is MEH-PPV/C ₆₀System, anode are the ITO that handles through PEDOT:PSS, negative electrode calcium (Ca) film of aluminium (Al) that has been the aluminium (Al) of vacuum evaporation or outer evaporation.[1：Dittmer J.；Lazaroni P.；Leclere P.；GranstromM.；Petritsch K.；Marseglia E.A.；Friend R.H.；Rost H.；Holmers A.B.SolarEnergy materials and Solar Cell，2000，61，53.2：Yu G.；Heeger A.J.J.Appl.Phys.Lett.，2000，77，17，2635]

The p-n junction type structure that is had with the inorganic semiconductor solar cell is different, polymer solar battery is to utilize the photoinduction electric charge from giving body/receptor type structure as the conducting polymer of electron donor (Donor) to what shift as the polymer of electron acceptor (Acceptor) or micromolecule, as MEH-PPV and C ₆₀System.Its photoinduction charge transfer process as shown in Figure 2.Because photoinduction charge transfer speed is at subpicosecond (subpicoseconds) order of magnitude, speed is 1000 times of the photoexciton radiation or the non-radiative rate of decay, thereby can think that electric charge approaches 1 in the quantum efficiency of giving body/acceptor interfacial separation.This ultrafast photoinduction electron transfer process has not only strengthened the generation of electric charge carrier in polymer, has also reduced compound again [the 1:Sariciftci N.S. of separated charge; Smilowitz L.; Heeger A.J.; Wudl F.Sciences, 1992,258,1474.2:Smilowitz L.; SariciftciN.S.; Wu R.; Gettinger C.; Heeger A.J.; Wudl F.Phys.Rev.B, 1993,47,13835.3:Brabec C.J.; Sariciftci N.S.; Hummelen J.C.Adv.Funct.Mater., 2001,11,15.].

But the efficient of polymer solar battery is lower at present, and for the MEH-PPV/C60 system, the energy conversion efficiency of white light only is 0.4%[1:Gao J. under the simulated solar irradiation; Hide F.; Wang.H.Synth.Met., 1997,84,979.2:Sariciftci N.S.; Heeger A.J.et al.Appl.Phys.Lett.1993,62,585].This mainly is because following factor causes: 1. effective separation of charge only occurs in the near interface to body/acceptor (D/A): the diffusion length of exciton has only about 10nm, thereby it is just compound before the exciton that produces away from the interface is being diffused into the interface, separation of charge is limited in very little zone, thereby the quantity of absorption photon will be restricted; 2. the electric charge after separating transmits between strand in the mode of jumping, and mobility is lower; 3. present polymeric material absorbing light wave-length coverage is narrow, sunlight is utilized insufficient.

Summary of the invention

The objective of the invention is to overcome existing polymer solar battery low defective of energy conversion efficiency under simulated solar irradiation, thus a kind of interpolation that can be used to improve the polymer solar battery energy conversion efficiency the is provided photo-conductive film of salt.

The objective of the invention is to be achieved through the following technical solutions:

The photo-conductive film that is used for the polymer photovoltaic cell provided by the invention, its main body comprise poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) and the C with 1: 1 or 1: 2 weight ratio ₆₀Be spin-coated on the laminated film on the electro-conductive glass after the mixing, it is characterized in that: also comprise interpolation salt, the described 1-5wt% that adds salt adding amount for poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) weight.

Add salt and comprise: slaine, organic ammonium salt and glyoxaline ion liquid salt.Wherein said slaine comprises LiN (CF ₃SO ₂) ₂Described organic ammonium salt comprises the tetrabutylammonium perchlorate; Described glyoxaline ion liquid salt comprises 1-methyl-3-cetyl imidazoles hexafluorophosphate.

Preparation provided by the invention is used for the photo-conductive film method of polymer photovoltaic cell, may further comprise the steps:

A. will gather (2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) and C ₆₀Be dissolved in the o-dichlorohenzene solvent with 1: 1 or 1: 2 weight ratio, wherein the percent weight in volume concentration of poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) is 0.5w/v%, C ₆₀Percent weight in volume concentration be 0.5 or 1w/v%, reflux also stirs and makes it dissolving evenly, obtains mixed liquor I;

The salt that b. will gather the 0-5wt% of (2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) weight is dissolved in acetonitrile or carrene or the tetrahydrofuran solvent, and splashes in the above-mentioned mixed liquor I, obtains mixed liquor I I;

The transparent conducting glass of c. having anticipated according to a conventional method is placed on the film applicator, and spin-coating, rotating speed are 1500-2500 rev/min, and mixed liquor I I is dropped on the electro-conductive glass, obtain translucent photo-conductive film.

The present invention has prepared to MEH-PPV/C ₆₀Add the photo-conductive film of different salt in the system.Using (Al) film of metallic aluminium on the conventional method evaporation or calcium film (Ca) on this photo-conductive film again, promptly prepared a polymer battery that adds salt as negative electrode.Under the condition of different luminous intensities and photovoltaic cell formation, the polymer photovoltaic cell has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, estimated the photovoltaic property of corresponding device.

The invention has the advantages that: the present invention is because at MEH-PPV/C ₆₀Add salt in the system, thereby changed the dipole character at polymer and metal electrode interface, improved the charge-trapping of photovoltaic cell; In addition, salt be incorporated as that separated charge provides anion, increased the stability of separated charge, therefore the transference cell in the abatement device adds the different systems of salt of the same race not, the polymer solar battery efficient of different metal electrode is improved at large.

Description of drawings

Fig. 1 is a battery structure schematic diagram of the present invention;

Fig. 2 is a photoinduction charge transfer process schematic diagram in the polymer solar battery;

Fig. 3 is the current-voltage characteristic curve of the polymer photovoltaic cell among the embodiment 3;

Drawing is described as follows:

1 is glass substrate; 2 is the ITO conductive layer;

3 is PEDOT:PSS resilient coating (i.e. poly-(3,4-epidioxy ethylthiophene): poly styrene sulfonate);

4 is photoactive thin film-layer; 5 is as the metal Ca of the vacuum evaporation of negative electrode or the electrode film of Al;

It is the current-voltage characteristic curve of 0% polymer photovoltaic cell that curve " ■ ■ ■ " is represented salinity;

Curve " ● ● ● " to represent salinity be the current-voltage characteristic curve of 1% polymer photovoltaic cell;

It is the current-voltage characteristic curve of 2% polymer photovoltaic cell that curve " ▲ ▲ ▲ " is represented salinity;

It is the current-voltage characteristic curve of 3% polymer photovoltaic cell that curve "    " is represented salinity;

Curve " ◆ ◆ ◆ " to represent salinity be the current-voltage characteristic curve of 5% polymer photovoltaic cell.

Specific embodiments

The present invention will be described in detail below in conjunction with preparation method of the present invention and Fig. 1:

Embodiment 1

With 5mg MEH-PPV and 5mg C ₆₀Be dissolved in the 1ml o-dichlorohenzene solvent, reflux and stirring make it dissolving evenly, obtain mixed liquor I; With 0.1mg LiN (CF ₃SO ₂) ₂Be dissolved in the 20 μ l acetonitrile solvents and splash in the above-mentioned mixed liquor I, obtain mixed liquor I I; Under 1500 rev/mins of rotating speeds, mixed liquor I I is dropped on the transparent conducting glass of being made up of glass substrate 1, ITO conductive layer 2 and PEDOT:PSS resilient coating 3 (anode) of having anticipated according to a conventional method, spin-coating promptly is coated with the translucent photo-conductive film 4 of last layer 100 nanometer thickness on anode.On this photo-conductive film 4, use metallic aluminium on the conventional method evaporation (Al) film 5 as negative electrode again, promptly prepared a polymer battery that adds 2wt% salt.

Add the salt of 0wt%, 1wt% and 3wt% respectively with same method, prepared the polymer battery of a series of different salinity.With the Halogen lamp LED light source, 85mW/cm ²The condition of luminous intensity under, this a series of polymer battery has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, it the results are shown in table 1.

System adds salinity	Jsc(mA/cm 2)	Voc(V)	FF	Efficient %
					0％	0.26	0.68	0.30	0.062
1％	0.30	0.72	0.27	0.069
					2％	0.63	0.73	0.30	0.160
3％	0.50	0.62	0.29	0.105

Table 1. has added LiN (CF ₃SO ₂) ₂The device performance of polymer battery.Wherein Jsc represents short circuit current; Voc is an open circuit voltage, and FF is a fill factor, curve factor, and efficient is the energy conversion efficiency under the white light.

As can be seen from Table 1: along with the increase of lithium salt, short circuit current increases thereupon.When reaching 2wt%, salinity reaches maximum 0.63mA/cm ², when salinity continuation increase, short circuit current reduces thereupon.Open circuit voltage is little in salinity hour variation, and salinity surpasses at 2% o'clock and reduces to some extent.Fill factor, curve factor changes little with salinity.The device energy conversion efficiency also presents the first trend that afterwards reduces that increases with the concentration increase of salt.When salinity 2wt%, reach maximum 0.16%.

Embodiment 2

With 5mg MEH-PPV and 10mg C ₆₀Be dissolved in the 1ml o-dichlorohenzene solvent, reflux and stirring make it dissolving evenly, obtain mixed liquor I; With 0.1mg LiN (CF ₃SO ₂) ₂Be dissolved in the 20 μ l acetonitrile solvents and splash in the above-mentioned mixed liquor I, obtain mixed liquor I I; Under 1500 rev/mins of rotating speeds, mixed liquor I I is dropped on the transparent conducting glass of being made up of glass substrate 1, ITO conductive layer 2 and PEDOT:PSS resilient coating 3 (anode) of having anticipated according to a conventional method, spin-coating promptly is coated with the translucent photo-conductive film 4 of last layer 105 nanometer thickness on anode.On this photo-conductive film 4, use metallic aluminium on the conventional method evaporation (Al) film 5 as negative electrode again, promptly prepared a polymer battery that adds 2wt% salt.

Add the salt of 0wt%, 1wt% and 3wt% respectively with same method, prepared the polymer battery of a series of different salinity.With the Halogen lamp LED light source, 85mW/cm ²The condition of luminous intensity under, this a series of polymer battery has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, it the results are shown in table 2.

System adds salinity	Jsc(mA/cm 2)	Voc(V)	FF	Efficient %
					0％	0.23	0.57	0.39	0.06
1％	0.41	0.63	0.38	0.11
					2％	0.76	0.60	0.32	0.17
3％	0.50	0.52	0.29	0.088

Table 2. has added LiN (CF ₃SO ₂) ₂The device performance of polymer battery.Wherein Jsc represents short circuit current; Voc is an open circuit voltage, and FF is a fill factor, curve factor, and efficient is the energy conversion efficiency under the white light.

As can be seen from Table 2: C ₆₀Ratio increases, and shows similar regularity with the device performance after the salt.

Embodiment 3

With 5mg MEH-PPV and 10mg C ₆₀Be dissolved in the 1ml o-dichlorohenzene solvent, reflux and stirring make it dissolving evenly, obtain mixed liquor I; With 0.1mg LiN (CF ₃SO ₂) ₂Be dissolved in the 20 μ l acetonitrile solvents and splash in the above-mentioned mixed liquor I, obtain mixed liquor I I; Under 1500 rev/mins of rotating speeds, mixed liquor I I is dropped on the transparent conducting glass of being made up of glass substrate 1, ITO conductive layer 2 and PEDOT:PSS resilient coating 3 (anode) of having anticipated according to a conventional method, spin-coating promptly is coated with the translucent photo-conductive film 4 of last layer 105 nanometer thickness on anode.On this photo-conductive film 4, use calcium metal on the conventional method evaporation (Ca) film 5 as negative electrode again, oxidized for preventing the Ca film, outside the Ca electrode, steam plated aluminum (Al) film again, promptly prepared a polymer battery that adds 2wt% salt.

Add the salt of 0wt%, 1wt%, 3wt% and 5wt% respectively with same method, prepared the polymer battery of a series of different salinity.With the Halogen lamp LED light source, 85mW/cm ²The condition of luminous intensity under, this a series of polymer battery has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, it the results are shown in table 3.

System adds salinity	Jsc(mA/cm 2)	Voc(V)	FF	Efficient %
					0％	0.899	0.67	0.33	0.236
1％	1.657	0.67	0.34	0.44
					2％	3.160	0.67	0.37	0.95
3％	1.384	0.68	0.38	0.416
					5％	1.316	0.61	0.33	0.315

Table 3. has added LiN (CF ₃SO ₂) ₂The device performance of polymer battery.Wherein Jsc represents short circuit current; Voc is an open circuit voltage, and FF is a fill factor, curve factor, and efficient is the energy conversion efficiency under the white light.

As can be seen from Table 3: after Ca was negative electrode, photoelectric current had greatly increased.After adding lithium salts, show short circuit current, the first regularity that afterwards reduces that increases of energy conversion efficiency equally.When lithium salt 2wt%, energy conversion efficiency reaches 0.95%.Its current-voltage characteristic curve as shown in Figure 3.Along with the increase that adds lithium salt, the photoelectric current of polymer photovoltaic cell increases obviously as seen from Figure 3, reaches maximum in salinity during for 2wt%, and when salinity continued to increase, photoelectric current reduced; And open circuit voltage variations is little; Thereby the regularity that afterwards reduces appears increasing earlier in energy conversion efficiency.

Embodiment 4

With 5mg MEH-PPV and 10mg C ₆₀Be dissolved in the 1ml o-dichlorohenzene solvent, reflux and stirring make it dissolving evenly, obtain mixed liquor I; Be dissolved in 0.1mg 1-methyl-3-cetyl imidazoles hexafluorophosphate in the 20 μ l acetonitrile solvents and splash in the above-mentioned mixed liquor I, obtain mixed liquor I I; Under 1500 rev/mins of rotating speeds, mixed liquor I I is dropped on the transparent conducting glass of being made up of glass substrate 1, ITO conductive layer 2 and PEDOT:PSS resilient coating 3 (anode) of having anticipated according to a conventional method, spin-coating promptly is coated with the translucent photo-conductive film 4 of last layer 95 nanometer thickness on anode.On this photo-conductive film 4, use calcium metal on the conventional method evaporation (Ca) film 5 as negative electrode again, oxidized for preventing the Ca film, outside the Ca electrode, steam plated aluminum (Al) film again, promptly prepared a polymer battery that adds 2wt% salt.

Add the salt of 0wt%, 1wt%, 3wt% and 5wt% respectively with same method, prepared the polymer battery of a series of different salinity.With the Halogen lamp LED light source, 85mW/cm ²The condition of luminous intensity under, this a series of polymer battery has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, it the results are shown in table 4.

System adds salinity	Jsc(mA/cm 2)	Voc(V)	FF	Efficient %
					0％	0.899	0.67	0.33	0.236
1％	1.92	0.58	0.37	0.48
					2％	1.74	0.60	0.40	0.50
3％	1.38	0.40	0.32	0.209
					5％	1.077	0.50	0.38	0.24

Table 4. has added the device performance of the polymer battery of 1-methyl-3-cetyl imidazoles hexafluorophosphate.Wherein Jsc represents short circuit current; Voc is an open circuit voltage, and FF is a fill factor, curve factor, and efficient is the energy conversion efficiency under the white light.

Embodiment 5

With 5mg MEH-PPV and 10mg C ₆₀Be dissolved in the 1ml o-dichlorohenzene solvent, reflux and stirring make it dissolving evenly, obtain mixed liquor I; Be dissolved in the 0.1mg tetrabutylammonium perchlorate in the 20 μ l acetonitrile solvents and splash in the above-mentioned mixed liquor I, obtain mixed liquor I I; Under 1500 rev/mins of rotating speeds, mixed liquor I I is dropped on the transparent conducting glass of being made up of glass substrate 1, ITO conductive layer 2 and PEDOT:PSS resilient coating 3 (anode) of having anticipated according to a conventional method, spin-coating promptly is coated with the translucent photo-conductive film 4 of last layer 90 nanometer thickness on anode.On this photo-conductive film 4, use calcium metal on the conventional method evaporation (Ca) film 5 as negative electrode again, oxidized for preventing the Ca film, outside the Ca electrode, steam plated aluminum (Al) film again, promptly prepared a polymer battery that adds 2wt% salt.

Add the salt of 0wt%, 1wt%, 3wt% and 5wt% respectively with same method, prepared the polymer battery of a series of different salinity.With the Halogen lamp LED light source, 85mW/cm ²The condition of luminous intensity under, this a series of polymer battery has been carried out the test of the energy conversion efficiency under short circuit current, open circuit voltage, fill factor, curve factor and the white light, it the results are shown in table 5.

System adds salinity	Jsc(mA/cm 2)	Voc(V)	FF	Efficient %
					0％	0.899	0.67	0.33	0.236
1％	1.12	0.52	0.40	0.284
					2％	1.25	0.49	0.37	0.265
3％	1.42	0.52	0.41	0.361
					5％	1.07	0.49	0.40	0.252

Table 5. has added the device performance of tetrabutylammonium perchlorate's polymer battery.Wherein Jsc represents short circuit current;

Voc is an open circuit voltage, and FF is a fill factor, curve factor, and efficient is the energy conversion efficiency under the white light.

Experimental result show salt not of the same race in different systems to device performance to influence trend basic identical: show short circuit current, energy conversion efficiency increases earlier the regularity that afterwards reduces, when salinity reaches the 2wt% left and right sides, device performance reaches peak, and does not add the salt face specific efficiency and improves 2-4 doubly.But when salinity continues to increase, will make the polyblend film produce apparent in view phase-splitting, device performance is had a negative impact.Best salt content is 2-3wt%.

Claims (4)

1, a kind of photo-conductive film that is used for the polymer photovoltaic cell, its main body comprise poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) and the C with 1: 1 or 1: 2 weight ratio ₆₀Be spin-coated on the laminated film on the electro-conductive glass after the mixing, it is characterized in that: also comprise interpolation salt, the described 1-5wt% that adds salt adding amount for poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) weight; Described interpolation salt is LiN (CF ₃SO ₂) ₂, tetrabutylammonium perchlorate or 1-methyl-3-cetyl imidazoles hexafluorophosphate.

2, by the described photo-conductive film that is used for the polymer photovoltaic cell of claim 1, it is characterized in that: the thickness of described photo-conductive film is in the 90-105 nanometer.

3, the described preparation method who is used for the photo-conductive film of polymer photovoltaic cell of a kind of claim 1, its method comprises the steps:

A. will gather (2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) and C ₆₀Be dissolved in the o-dichlorohenzene solvent with 1: 1 or 1: 2 weight ratio, wherein the percent weight in volume concentration of poly-(2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) is 0.5w/v%, C ₆₀Percent weight in volume concentration be 0.5 or 1w/v%, reflux also stirs and makes it dissolving evenly, obtains mixed liquor I;

The salt that b. will gather the 1-5wt% of (2-methoxyl group-5-(2 '-ethyl-own oxygen base)-1,4-supports styrene) weight is dissolved in acetonitrile or carrene or the tetrahydrofuran solvent, and splashes in the above-mentioned mixed liquor I, obtains mixed liquor I I;

The transparent conducting glass of c. having anticipated according to a conventional method is placed on the film applicator, and spin-coating, rotating speed are 1500-2500 rev/min, and mixed liquor I I is dropped on the electro-conductive glass, obtain translucent photo-conductive film.

4, the described application that is used for the photo-conductive film of polymer photovoltaic cell at the polymer photovoltaic cell of a kind of claim 1.

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