Vertical phase separation and light-soaking effect improvements by photoactive layer spin coating initiation time control in air-processed inverted organic solar cells

Jeon, Ii; Matsuo, Yutaka

doi:10.1016/j.solmat.2015.04.017

Cited by 26 publications

(19 citation statements)

References 52 publications

(63 reference statements)

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“…The P3HT domains have mutually connected band-like shapes, which is a characteristic of a percolationtype phase-separated morphology. The film also exhibited features of vertical phase separation: [25][26][27][28] the P3HT domains were gathered around both electrodes, and the bis-PCBM domains were localized in the bulk center of the film. Figure 6b shows a cross-sectional image of a cell that was treated with a combination of longer drying times (t 1 = 500 s; t 2 = 10 m) and post-annealing (150…”

Section: Resultsmentioning

confidence: 99%

Effect of Drying Time on Morphology and Photovoltaic Characteristics of Polymer Solar Cells of Bis-PCBM/P3HT Composites

Nagai

Gao

Huang

et al. 2016

ECS J. Solid State Sci. Technol.

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Slow drying has been proposed as a way to improve the performance of polymer solar cells (PSCs) where the drying time for the coated films is increased using a condensed solvent vapor atmosphere. This work investigated the slow drying mechanism by using PSCs consisting of poly(3-hexylthiophene-2,5-diyl) (P3HT) and bis-[6,6]-phenyl-C61-butyric acid methyl ester (bis-PCBM) and focusing on the phase-separated morphology of bulk heterojunction films. With conventional spin casting, the power conversion efficiency (PCE) of the cells was very low (0.83%). The application of slow drying resulted in notable improvements in the short-circuit current density (5.85 → 8.07 mA/cm 2 ) and fill factor (0.12 → 0.55). Optimization of the thermal annealing and cathode interfacial conditions resulted in a high PCE of 4.05%. As the drying time was increased, the P3HT domains changed from connected band-like shapes to small separated ball-like shapes. The mechanism for this effect of slow drying on the bis-PCBM/P3HT cell characteristics is understood as follows: The slow drying causes the P3HT domains to separate into small pieces, which causes the area of the p−n interfaces to increase, resulting in an increase in free carrier generation and increased the short-circuit current density of PSCs. Organic photovoltaics have been actively studied as a major candidate for use in next-generation solar cells due to the several advantages they possess, including light weight, thin film, and low material cost.1-3 In particular, polymer solar cells (PSCs) can be made by applying a solution of p-type polymers and n-type fullerene-based small molecules, meaning that PSCs do not require expensive vacuum equipment, which can potentially reduce processing costs. The efficiency of PSCs has been drastically improved over the past decade. A cell efficiency of more than 10% has already been reported. 4 However, further improvement in efficiency is crucial for practical use.The performance of PSCs depends not only on the materials used but also their processing conditions. Thermal annealing 5-8 and solvent annealing 9-11 are representative techniques for improving solar cell performance. These methods have been extensively studied, and their effects on the short-circuit current density (J sc ) of PSCs have been clarified. They enhance the crystallinity of the constituent materials 5,6,9,10 and thereby increase the carrier mobility, leading to higher J sc .Unfortunately, these methods are problematic. Thermal annealing can only be applied to certain polymers, and solvent annealing requires an extremely long processing time (normally several hours). 10Another proposed method is "slow drying," in which the drying time of the coated films is reduced by increasing the solvent vapor pressure of the film coating atmosphere. [12][13][14][15] This method also effectively increases the J sc of PSCs. While this method resembles solvent annealing, it has a much shorter treatment time (10−20 min). Therefore, from the viewpoint of mass-manufacturing, slow drying has...

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Section: Resultsmentioning

confidence: 99%

Effect of Drying Time on Morphology and Photovoltaic Characteristics of Polymer Solar Cells of Bis-PCBM/P3HT Composites

Nagai

Gao

Huang

et al. 2016

ECS J. Solid State Sci. Technol.

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“…The blend morphology of electron-donating polymer and fullerene acceptor is sensitive to processing conditions. There have been substantial efforts in process engineering to attain desired morphology in polymer-fullerene bulk heterojunction, particularly P3HT-PCBM system 15 – 19 . With optimization of solution processing conditions, uniform morphology in the lateral direction could typically be obtained.…”

Section: Introductionmentioning

confidence: 99%

Effect of Donor-Acceptor Vertical Composition Profile on Performance of Organic Bulk Heterojunction Solar Cells

Ouyang

Shaik

et al. 2018

Sci Rep

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In organic bulk heterojunction solar cells (OSCs) donor-acceptor vertical composition profile is one of the crucial factors that affect power-conversion efficiency (PCE). In this simulation study, five different kinds of donor-acceptor vertical configurations, including sandwich type I and type II, charge transport favorable, charge transport unfavorable, and uniform vertical distribution, have been investigated for both regular and inverted OSC structures. OSCs with uniform and charge transport favorable vertical composition profiles demonstrate the highest efficiencies. High PCE from charge transport favorable configuration can be attributed to low recombination because of facilitated charge transport in active layer and collection at electrodes, while high PCE from uniform structure is due to sufficient interfaces for efficient exciton dissociation. OSCs with sandwich and charge transport unfavorable structures show much lower efficiencies. The physical mechanisms behind simulation results are explained based on energy band diagrams, dark current-voltage characteristics, and comparison of external quantum efficiency. In conclusion, experimental optimization of vertical composition profile should be directed to either uniform or charge transport favorable vertical configurations in order to achieve high-performance OSCs.

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“…Despite being a less expensive technology, the loss of a large amount of solution makes this technique incompatible with the promising large-scale roll-toroll. 3,7,8,11,14,[45][46][47] Spin coating was used to form the donor G-P3HT in as mentioned the study 48 and the active layers P3HT:PCBM in the studies, 17,36,45,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] P3HT:MIF in the study, 62 P3HS: PCBM in the study, 66 PTB7:PCBM in the study, 67 PTB7: PC 70 BM in the study, 68 PTB7:PC 71 BM and PTB7-Th: PC 71 BM in the study, 69 PBDB-T-SF:IT-4F in the study, 70 PBDB-T:PC 71 BM in the study, 71 PBDB-TSR:PC 71 BM in the study, 72 PBDB-T:ITC in the study, 73 PTB7-Th:PC 71 BM in the study, 74 P3HT:ICBA in the studies, 39,75-77 PTB7: PC 71 BM:P-GO in the study, 78 MEH-PPV:PCBM in the study, 79 ZnPc-TB:PTCBI in the study, 80 PEHBDT-DFDTBSe:PC 71 BM in the study, 75 PBDTTT-C:PCBM in the study, 81 PBDTT-F-TT:diPBI in the study, 82 PBDB-T: FH, PBDB-T:FM, PTB7-Th:NFBDT, and PTB7-Th:NOBDT in the study, 83 PSBTBT:PDI-DTT in the study, 84 PDBT-T1: SdiPBI-S in the study, 85 PBDT-8:PC 71 BM and PTIPSBDT-DFDTQX:PC 71 BM in the study 86…”

Section: Spin Coatingmentioning

confidence: 99%

Overview of printing and coating techniques in the production of organic photovoltaic cells

et al. 2020

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The organic photovoltaic cell (OPV) is composed of multiple layers, and some printing and coating techniques are more suitable than others for a certain type of layer. This paper aims to characterize and compare the most relevant coating and printing techniques that can be used in the manufacture of OPVs. Extensive bibliographic research was carried out on articles published from 1998 to 2020 to identify various aspects OPV, such as the principle of operation, advantages, disadvantages, and which layers can be printed by each technique. The results show that the most used method for the processing of OPVs is spin-coating. In the studies found, rotation was used to coat the active layer, the electron transport layer, and the hole transport layer. The techniques of pad printing, casting, and meniscus are considered useful in the processing of the active layer. Regarding the deposition of the active layer, hole transport layer, electron transport layer, and anode, the rotogravure, crack matrix, spraying, and brushing techniques were satisfactory. Flexography has been used to form the active layer, electron transport layer, and anode. Screen printing, inkjet printing, and knife/blade coating were used in the processing of the active layer, hole transport layer, electron transport layer, anode, and cathode. All the double slot die coating, curtain coating, and slide coating allows simultaneous processing of multiple layers. Techniques compatible with roll-to-roll processing are more likely to be at the center of OPVs in the future, thus making solar photovoltaic technology more competitive.

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Vertical phase separation and light-soaking effect improvements by photoactive layer spin coating initiation time control in air-processed inverted organic solar cells

Cited by 26 publications

References 52 publications

Effect of Drying Time on Morphology and Photovoltaic Characteristics of Polymer Solar Cells of Bis-PCBM/P3HT Composites

Effect of Drying Time on Morphology and Photovoltaic Characteristics of Polymer Solar Cells of Bis-PCBM/P3HT Composites

Effect of Donor-Acceptor Vertical Composition Profile on Performance of Organic Bulk Heterojunction Solar Cells

Overview of printing and coating techniques in the production of organic photovoltaic cells

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