Highly Efficient and Operational Stability Polymer Solar Cells

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Organic Electronic Devices

Highly Efficient and Operational Stability Polymer Solar Cells Employing Non-Halogenated Solvent and Additive Jiao Zhao, Suling Zhao, Zheng Xu, Dandan Song, Bo Qiao, Di Huang, Youqin Zhu, Yang Li, Zicha Li, and Zilun Qin ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b07342 • Publication Date (Web): 22 Jun 2018 Downloaded from http://pubs.acs.org on June 22, 2018

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ACS Applied Materials & Interfaces

Highly Efficient and Operational Stability Polymer Solar Cells Employing Non-Halogenated Solvent and Additive Jiao Zhao, †,‡ Suling Zhao,*, †,‡ Zheng Xu, †,‡ Dandan Song, †,‡ Bo Qiao, †,‡ Di Huang, †,‡ Youqin Zhu, †,‡ Yang Li, †,‡ Zicha Li, †,‡ and Zilun Qin†,‡

† Key Laboratory of Luminescence and Optical Information (Beijing Jiaotong University),

Ministry of Education, Beijing, 100044, China ‡ Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing, 100044, China

ABSTRACT: The power conversion efficiencies (PCEs) of important application potential polymer solar

cells

(PSCs)

have

been

rapidly

exceeded

15%.

However,

these

high-performance devices are based on halogenated solvents that pose a significant hazard to the atmospheric environment and human beings. The use of non-halogenated solvents makes the device less efficient due to its solubility issues. In this contribution, we report high efficiency devices utilising PffBT4T-2OD and PC71BM system, from non-halogenated solvents as o-xylene (o-XY) and 1-Methylnaphthalene (Me) hydrocarbon solvent. When Me was used as the additive, the power conversion efficiency of prepared devices improved from 1.83% to 10.13%, which is rather higher than that of devices processed with traditional solvents combinated with CB and DIO (8.18%). Both AFM and TEM confirmed that after non-halogen solvents are treated, a more finely phase-separated dense morphology of active layers than after halogen solvents. At the same time, GIWAXS pattherns show that the combination of non-halogenated solvents o-XY and Me ingeniously formed an ordered crystal and π-π stacking. Also, the stability of devices prepared from non-halogenated solvents was significantly better than that of halogenated solvents under continuous illumination in the air without encapsulation. KEYWORDS: non-halogenated, morphology, high efficiency, device stability,

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environmentally friendly

INTRODUCTION Polymer solar cells (PSCs) based on bulk-heterojunction (BHJ) structures regard as a kind of green energy with great development potentials and application values at present due to their simple manufacturing process, low energy consumption, and flexible by roll-to-roll printing techniques to a large-scale.1-7 However, the state of the art PSCs with a higher efficiency are processed by very toxic halogenated solvents, for instance chloroform (CF), o-dichlorobenzene (DCB), chlorobenzene (CB) and so on, which are harmful to human health and the environment and limit the commercialization and environmental sustainability of PSCs. These halogenated solvents play a critical role in the fabrication of PSCs to form a good film and a relative small phase seperation domain in the active layer because of their strong solvency to polymers with conjugated structures as electron donors and PC61BM/PC71BM as electronic receptors.8-10 Additionally, additives containing halogenated elements such as 1,8-diiodooctane (DIO) and 1-chloronaphthalene(CN), are generally used as a class of solvents necessary for high performance PSCs to improve the solubility of one of the components in the active layer, and at the same time, they can optimize the microstructure of the active layer and thus the photoelectric performance of the device can be greatly increased.11-14 But it has been shown in recent reports that DIO is a typical representative of halogen-containing additives can residue in the active layer and constrict PSCs stability and reproducibility.15-16 Consequently, it is a major challenge to overcome the problems that are caused by this solution method in the preparation of solar cells that are not conducive to industrialized flexible production and environmental pollution. The search for a special combination of low toxicity non-halogenated solvents is an effective way to solve this problem. The solubility and film formation process of organic materials in aromatic non-halogenated solvents also have similar characteristics with halogenated solvents


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in the preparation of organic solar devices by solution method. However, the photoelectric conversion efficiency of most devices fabricated using non-halogenated solvents to date has been lower than that of conventional halogenated solvents.17-20 Generally,

non-halogenated

solvents

include

some

hydrocarbons

such

as

tetrahydrofuran, toluene, o-xylene, and the like, and these solvents produce devices with low efficiency because of their low solubility to donor polymer materials and acceptor PCBM materials. It has been reported that the active layer prepared with o-xylene has a very poor morphology, and an island-like aggregate of approximately 500 nm is formed on the surface of the film, mainly due to the very low solubility of the fullerene derivative (o-xylene= 5.2 mg/mL).21-23 Recently, it is worth mentioning that the PSCs prepared by using a full hydrocarbon solvent 1,2,4-trimethylbenzene (TMB) and with 2.5% 1-phenylnaphthalene (PN) system has very excellent performance, and the photoelectric conversion efficiency exceeds 10%.19, 24 PN, has almost the same high boiling point of 320 ℃ as 1,8-diiodooctane (DIO), easily remain in a thick active layer and accelerates the device aging. This is also a place worthy of attention in the later industrial production. The ingenious cooperation between non-halogenated solvents and non-halogenated additives is the key to the preparation of high-efficiency organic solar cells using the full hydrocarbon solution method. What’s more, additives play an important role in the optimization of the active layer morphology of organic solar cells.25-29 In order to realize all non-halogenated solvents to prepare high-performance PSCs, 1-Methylnaphthalene (Me) meets the demand as the matched additive, a) higher solubility of the fullerene derivative than the main solvent; b) lower boiling point (Me, 240 ℃) than the general addictive (DIO, 333 ℃) . Me is not easily remained in the thick active layers; c) Me contains only C and H elements and its chemical structure is stable. Meanwhile, there is no light oxidation to the active layer, which will improve the device lifetime significantly.16, 30 Therefore, the non-halogenated solvent Me is selected as the processing additive to optimization the morphology of the active layer in this paper. Here, we demonstrate a non-halogenated binary solvent system consisted with o-XY and Me as processing ACS Paragon Plus Environment


solvents to make highly efficient PSCs based on PffBT4T-2OD:PC71BM. Results indicate that the hydrocarbon solvent system composed of non-halogenated solvent o-XY+Me can produce better performance in high effciency, environmental-friendly and stability than traditional halogenated solvent CB/DIO or DCB/DIO mixture system.

EXPERIMENTAL SECTION PSCs were fabricated according to the device architecture demonstrated Figure 1a. First, the glass substrate with the transparent electrode of indium tin oxide was cleaned and cleaned ultrasonically in a cleaning agent, deionized water, and ethanol for 30 minutes, respectively. Then dry it with nitrogen. Then, the dried ITO was placed face-up in an ultraviolet ozone cleaner and the surface was cleaned again for 30 minutes. After the ITO surface is cleaned, an electron transport layer is prepared. The ZnO precursor was prepared by dissolving zinc acetate dihydrate and ethanolamine in 2-methoxyethanol, and the ZnO precursor solution was spin-cast on the top of ITO substrates and then annealed at 150 °C for 30 min in the air. It was transferred to a glove box filled with inert gas for use. The donor material polymer PffBT4T-2OD was purchased from 1-Material company and PC71BM purchased from Nano-C. The solvent used was purchased in sigma. The donor material and the acceptor material were mixed into a solution having a total solution concentration of 32.2 mg/ml according to a mass ratio of 1:1.3. The main solvents were CB and o-XY, respectively, and then heated and stirred at 100 ℃ overnight. Additives DIO and Me were added to CB and o-XY, respectively, 1 hour before the active layer preparation. When the active layer is prepared, the ITO glass substrate with the ZnO layer and the prepared mixed drug are placed on a heating platform at 100 ℃ and then the hot solution is spin-coated at 1000 rpm for 25 seconds, and finally the prepared activity is achieved and was annealed at 80 °C for 10 minutes. Finally, a bilayer stack of 10 nm MoO3/100 nm aluminum was thermally evaporated as anodes under vacuum (2.0×10-4 Pa). The effective area of the device is 4 mm2. The tests involved in this article are all in the atmosphere. The current density-voltage (J-V) of the devices were measured by


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a Keithley 2400 source meter under simulated AM 1.5G illumination (100 mW/cm2). The surface morphology and network structure of the active layer were measured by atomic force microscope (AFM) by a multimode Nanoscope IIIa operated and transmission electron microscope (TEM) on a JEM-1400F transmission electron microscope operating at an acceleration voltage of 80 kV, respectively. The external quantum efficiencies (EQEs) data were recorded using a Zolix Solar Cell Scan 100. The UV-vis absorption spectra of active layers were acquired by a Shimadzu UV-3101 PC spectrophotometer. Grazing incident wide-angle X-ray scattering (GIWAXS) measurements were performed at the 1W1A with an incident angle was 0.2°.

Figure 1. (a) the device architecture of PSCs; (b) the materials and the solvents were used in PSCs

RESULTS AND DISCUSSION The microscopic morphology of the active layer plays a decisive role in the generation and transmission of charge in the device.31-32 Firstly, we investigated the effects of non-halogenated solvents and halogenated solvents and additives on the morphology of PffBT4T-2OD:PC71BM blend films, the surface and bulk morphologies of four blend films processed with CB (halogenated), CB+3% DIO (halogenated), o-XY (non-halogenated) and o-XY+3% Me (non-halogenated) were characterized by atomic force microscopy (AFM) and transmission electron



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microscope (TEM), respectively. As shown in Figure 2a and 2b, The active layer prepared from CB and CB+3% DIO showed almost no obvious change from the AFM topography, and its surface roughness was 3.3 nm and 3.5 nm, respectively. However, there are some obvious differences in the reticular structure in the TEM images (Figure 2e and 2f), which of the film with pure CB is vague, and the structure of the dendrite network was clearly observed after the addition of DIO. It indicates that the additive DIO promotes the crystallization of the polymer during the film formation. However, there are still large-scale black gathering areas. In non-halogenated solvent systems, there is a clear difference between the addition of additives and the absence of active layer morphology. Based on the results of AFM measurements (see Figure 2c and 2d), the addition of non-halogenated additive 3% vol Me to the active layer has greatly optimized the surface morphology of the blend film. The addition of Me decreased the roughness of the blend film surface from 25.2 nm (o-XY) to 2.9 nm (o-XY+3% Me). When non-halogenated systems do not add additives, a large number of spherical aggregates appear on the surface of the active layer, approximately 300-500 nm in diameter, which can be clearly seen in Figures 2c and 2g. In the TEM image, the globular aggregates appear as black areas and should be PC71BM aggregates because of their low solubility in o-XY.33 We know that proper phase separation is essential in order to maximize dissociation of excitons and bicontinuous interpenetrating networks to transport two carriers seperatelly. The phase separation of a few hundred nanometers in the active layer film prepared in o-XY results in a separation platform with less exciton dissociation and

increased exciton

recombination, which leads to lower overall device performance. Miraculously, when a small amount of non-halogenated additive Me was added, the spherical aggregates completely disappeared, a fine network structure was formed, and the microscopic morphology of the active layer was greatly optimized in Figure 2h. Although the active layer prepared by the halogenated solvent CB formed a better morphology than the non-halogenated solvent o-XY, a better microscopic morphology was formed when the non-halogenated additive Me was added. These results imply that o-XY+Me also can offer a better morphology in processing polymer:PCBM blend film, which ACS Paragon Plus Environment

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may change the situation that low-toxicity non-halogenated solvents cannot produce high-performance organic solar cells.

Figure 2. AFM topography (a, b, c, d) and TEM (e, f, g, h) images of optimized PffBT4T-2OD:PC71BM blends spin-coated from: (a) CB, (b) CB containing 3% DIO, (c) o-XY, (d) o-XY containing 3% Me respectively. To futher compare the effect of non-halogenated solvent o-XY and o-XY+Me on the film formation, the molecular packing of the active layer films as a function of the different host solvent /and addtives were investigated by 1D grazing incidence X-ray diffraction (GIXRD) and 2D grazing incidence wide-angle X-ray scattering (GIWAXS). In the out-of-plane (OOP) detection mode, the qz direction indicates that the crystal direction is parallel to the substrate direction that is the face-on direction, and in the in-plane (IP) detection mode, the qxy direction means the crystal direction is perpendicular to the substrate direction, ie, the edge-on direction. From the 2D GIWAXS images (Figure 3a-d), we can intuitively see the influence of halogenated and non-halogenated solvents and their additives on the out-of-plane and in-plane direction crystallinity of polymers and PCBM in films. As shown in Figure 3e and 3f, there is a significant difference in polymer crystallinity and orientation of films processed by different solvents. A very weak lamellar (100) peak located at q ≈ 0.3 Å-1 are observed from the 1D OOP direction of the active layer processed with halogenated solvents CB and DIO. However, when non-halogenated solvents o-XY and Me are used, the crystallinity of the alkyl chain is greatly increased and lamellar



(300) peak even is appeared. It shows that o-XY promotes the accumulation of alkyl chains in the face-on direction. Diffraction peaks of PCBM (The broad peaks at q≈ 1.33 Å−1 are characteristic of PC71BM aggregation) and a (010) peak located at q ≈ 1.7 Å-1 are significantly observed when a small amount of additives are added, especially added Me . It is concluded that the additive Me plays a positive role in the film formation process. At the same time, the crystallization in the edge-on direction is much weaker than the face-on direction, and it is contrary to the out-of-plane crystallization rule. The perfect combination of the non-halogenated solvent o-XY and the additive Me resulted in a significant increase in the crystallinity of the polymer and the PCBM parallel to the substrate, which facilitates the effective charge transport.


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(e) Intensity(a.u.)

CB CB+DIO o-XY o-XY+Me

out-of-plane

(100)

(PCBM)

(200)

(010)

(300)

0.5

1.0

1.5 O

2.0

qZ( A ) -1

(f)


in-plane

(100)

Intensity(a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(200)

(PCBM) (300) (010)

0.5

1.0

1.5 o

2.0

-1

qxy( A ) Figure 3. Two-dimensional GIWAXS images of the PffBT4T-2OD:PC71BM active layers processed from (a) CB, (b) CB containing 3% DIO, (c) o-XY, (d) o-XY containing 3% Me respectively, (e) GIXRD with out-of-plane and (f) in-plane scattering geometry for PffBT4T-2OD:PC71BM films with different additive. Above results show that non-halogenated solvents o-XY and Me can be used as the processing solvents to prepared PffBT4T-2OD:PC71BM blend films with a good film quality and a phase seperation. In order to understand the dependence of photovoltaic characteristics on these solvents, a series PffBT4T-2OD:PC71BM BHJ solar cells processed with halogenated and non-halogenated solvents were prepared. Table 1



summarizes the photovoltaic parameters of these devices. The best PCE of the device prepared in the micture solvent of o-XY and 3% Me is 10.13%, with a short circuit current density (Jsc) of 18.61 mA/cm2, an open-circuit voltage (Voc) of 0.75 V and a fill factor (FF) of 72.6%. In the non-halogenated solvent system, if Me is not added, the photoelectric conversion efficiency of the prepared device is only 1.83%, which is much lower than that of the halogenated solvent system. However, when a small amount of non-halogenated additive Me was added, both the short-circuit current and the fill factor were greatly improved, which is higher than the Jsc 16.23 mA/cm2 and the FF 67.2% of the device prepared by the conventional halogenated solvent CB+DIO combination. The significant increase in Jsc and FF was mainly attributed to the fact that the additive Me promoted the formation of a fine interpenetrating network structure of the active layer and an appropriate microscopic morphology of the donor and acceptor phase separation dimensions. This increases the probability of exciton dissociation and the effective transmission of charge. The device fabricated with o-XY+Me has the largest parallel resistance and the smallest series resistance, which is also an important reason for its large fill factor. We also compared the single-electron device mobility and single-hole device mobility prepared with halogenated solvent combination CB+DIO and non-halogenated solvent combination o-XY+Me, as shown in Figure. S2 and Table S2. We can see that the combination of o-XY+Me has larger electron mobility and hole mobility than the device prepared with CB+DIO combination, and electrons and holes are more balanced. This coincides with a large increase in short-circuit current and fill factor. We also studied the effect of different added volume ratios of Me on device performance as shown in Figure. S1 and Table S1. Among them, the best performance is a high PCE of 10.13% achieved by using 3% Me as the additive. As shown in Figure 4b, there are significant differences between halogenated and non-halogenated solvent systems. First, the EQE of the device fabricated by o-XY+Me combination is the highest, followed by the CB+DIO combination, and finally the single o-XY, the EQE change basically corresponds to the J-V curve. It is concluded that the ehanced performance is reulted mainly from the improved charge generation and efficient charge transfer ACS Paragon Plus Environment

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due to the effective phase seperation and good crystallization. The UV-vis absorption spectra of the blend films spin-cast with different solution in the same preparation conditions are displayed in Figure S3. These spectra exhibit significant differences. In the absence of additives, the characteristic absorption peaks of the donor material and the acceptor material in the active layer prepared from CB are more pronounced than that of the active layer prepared from o-XY solvent. After adding additives, the UV absorption was enhanced and the relative height of the characteristic peaks was improved, indicating that the additive has a certain guiding effect on the orderly packing of molecules and the interaction between molecules during the film formation process. (b)

(a) 2


0 -2 -4

100


90 80 70

-6

EQE(%)

Current density(mA/cm 2)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


-8 -10 -12

60 50 40 30

-14 -16

20

-18

10 0 300

-20 0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

400

Voltage(V)

500

600

700

800

Wavalength(nm)

Figure 4 J-V (a) and EQE (b) curves based on PffBT4T-2OD: PC71BM processed from CB, CB+3% DIO, o-XY and o-XY+3% Me. Table 1 Detailed photovoltaic parameters of PffBT4T-2OD:PC71BM based devices with different processing solvent and addictive. The average PCE were obtained from 20 devices. Device

Voc [V]

Jsc

Jsc (EQE) 2

[mA/cm ]

2

[mA/cm ]

FF

PCEmax

PCEage

Rs

Rsh

[%]

[%]

[%]

[Ωcm2]

[Ωcm2]

CB

0.75

14.95

14.86

62.5

6.91

6.87

6.06

577.82

CB+DIO

0.75

16.23

16.03

67.2

8.18

8.09

5.78

1134.33

o-XY

0.76

5.28

4.97

45.6

1.83

1.78

24.73

541.69

o-XY+Me

0.75

18.61

18.16

72.6

10.13

9.89

3.66

2082.44

The use of halogenated solvents has been a major problem for environmental issues and safety issues in the industrialization of PSCs, it has also been found that the use of halogenated additives such as DIO and CN has an important influence on the light



stability of the device.34 Moreover, the stability of the active layer morphology is also negatively impact by the solvent used and the addition.35-37 Therefore, we investigated the stability of PSCs with halogen and non-halogenated solvents. The photo-stability of the CB+DIO and o-XY+Me processed devices, under atmosphere and solar simulator, were studied the effect of different solvents and additives on the stability of the device. Figure 5a shows the UV-vis absorption data of the photoactive layer kept in air under AM 1.5G illumination for different storage times. As the storage time in air (under illumination) increases, the characteristic absorption of the active layer film prepared by halogenated solvents have obvious decrease in the whole spectrum range, especially in the characteristic absorption peak of PCBM (380 nm) and polymer (463 nm, 628 nm, 698 nm). It indicates the decomposition of a conjugated ring structure or broken conjugation on the PCBM and polymer backbones, which has been reported as a primary cause of solar cell degradation in recent studies.20 The decomposition of polymer chain backbones consequently results in a reduction in solar cell parameters, particularly Jsc and the fill factor, which degrade from 16.23 to 10.51 mA/cm2 and 67.2% to 51.6%, respectively (Table S3, Supporting Information). Consequently, the PCE significantly drops from 8.18% to 3.20% (60.33% loss) (Figure 5b). More importantly, the use of non-halogenated solvents appears to impede the photooxidation of organic films. Figure 5c shows the UV-vis absorption data for composite films processed with o-XY+Me as the time exposed in air and illuminated by AM1.5G. Even after a 12 h exposed in air and with the illumination, no damage to the chromophores of the conjugated molecules was found. At the same time, we tested the TEM of fresh and air-illuminated active layer films (Figure S4). It was found that a large amount of black aggregates appeared after the aging of the active layer prepared from the halogenated solvents. The active layers prepared from the non-halogenated solvents did not show any significant differences before and after aging. Consequently, Jsc and fill factor only reduce from 18.61 to 15.92 mA/cm2 and 72.6% to 57.1%, respectively (Table S4, Supporting Information). Consequently, the PCE decreases from 10.13% to 6.45% (36.35% loss) can be observed in Figure 5d. It can be estimated that non-halogenated solvents have less damage to donor and ACS Paragon Plus Environment

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acceptor materials in air with the light illumination because of the stable molecular structures of these solvents consisting of stable carbon and hydrogen atoms. (b) current density(mA/cm2)

Intensity(a.u.)

(a)

CB+DIO-0 h CB+DIO-1 h CB+DIO-3 h CB+DIO-6 h CB+DIO-12 h

2

CB+DIO-0 min CB+DIO-10 min CB+DIO-30 min CB+DIO-60 min

0 -2 -4 -6 -8 -10 -12 -14 -16

400

500

600

700

0.0

0.1

0.2

Wavalength(nm)

0.3

0.4

0.5

0.6

0.7

Voltage(V)

(c)

(d) current density(mA/cm2)

2

Intensity(a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


o-XY+Me-0 h o-XY+Me-1 h o-XY+Me-3 h o-XY+Me-6 h o-XY+Me-12 h

o-XY+Me-0 min o-XY+Me-10 min o-XY+Me-30 min o-XY+Me-60 min

0 -2 -4 -6 -8 -10 -12 -14 -16 -18

400

500

600

700

0.0

0.1

Wavalength(nm)

0.2

0.3

0.4

0.5

0.6

0.7

Voltage(V)

Figure 5. The active layer films and photovoltaic devices prepared by halogenated solvents (CB+DIO) and non-halogenated solvents (o-XY+Me), with the increase of the exposure time, the UV–vis absorption (a) and (c) and the J-V characteristics (b) and (d), respectively, in air with light illumination.

CONCLUSIONS We successfully applied non-halogenated, low-toxic solvent o-XY+Me to produce a highly efficient and relatively stable organic solar device based on the PffBT4T-2OD:PC71BM system. The device's photoelectric conversion efficiency has increased from 8.18% ( CB+DIO) to 10.13% (o-XY+Me).Compared to traditional halogenated solvent and additive combination prepared active layer non-halogenated solvent and additive combination to form a more smooth surface, a more compact network structure and the polymer in the face-on direction stacking is more orderly and crystallinity enhanced. Moreover, the non-halogenated mixture solvent (o-XY+3%



Me) under the conditions of continuous illumination in the air, the photoelectric properties of the device ensure the relative stability. The introduction of non-halogenated solvents and additives into the solution process for the preparation of organic solar cells will greatly promote the subsequent large-scale roll-to-roll industrial production, making it a truly clean energy source that is environmentally friendly and harmless to human health.

SUPPORTING INFORMATION Supplementary information available: Different additive ratios of additives on device performance. Hole and electron only mobilities of the blends. UV-vis absorption of active layer. Attenuation of devices under different conditions. TEM images of morphology attenuation.

AUTHOR INFORMATION Corresponding Author *E-mail address: [email protected], Tel (Fax):86-10-51684462. Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was supported by the Fundamental Research Funds for the Central Universities with the Grant No. 2017YJS202; the Fundamental Research Funds for the National Natural Science Foundation of China (No. 61575019 and 11474018); the National Key Research and Development Program of China under Grant No. 2016YFB0401302 and the key project of Beijing Scientific Committee No. D161100003416001. Part of this work was fulfilled on the basis of data acquired at 1W1A, BSRF. The authors deeply appreciate the assistance of scientists of Diffuse X-ray Scattering Station in the experiments.

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Table of Contents

o-XY+Me 2

Current density(mA/cm2)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0 -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 0.0

0.1

0.2

0.3

0.4

0.5

0.6

Voltage(V)


0.7

Highly Efficient and Operational Stability Polymer Solar Cells

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