Nanometer-Scaled Landscape of Polymer:Fullerene Blends Mapped with Visible s-SNOM

2021 ◽  
Author(s):  
Ya-Rong Lee ◽  
Cheng-Chia Huang ◽  
Wen-Yu Huang ◽  
Chin-Ti Chen ◽  
Ping-Tsung Huang ◽  
...  
Keyword(s):  
Active Layer ◽  
Organic Solar Cells ◽  
Charge Separation ◽  
High Performance ◽  
Bulk Heterojunction ◽  
Near Field ◽  
Photovoltaic Performance ◽  
Energy Landscapes ◽  
Donor And Acceptor ◽  
Shed Light

Abstract Bulk heterojunction is one key concept leading to breakthrough in organic photovoltaics. The active layer is expectantly formed of distinct morphologies that carry out their respective roles in photovoltaic performance. The morphology-performance relationship however remains stymied, because unequivocal morphology at the nanoscale is not available. We used scattering-type scanning near-field optical microscopy operating with a visible light source (visible s-SNOM) to disclose the nanomorphology of P3HT:PCBM and pBCN:PCBM blends. Donor and acceptor domain as well as intermixed phase were identified and their intertwined distributions were mapped. We proposed energy landscapes of the BHJ active layer to shed light on the roles played by these morphologies in charge separation, transport and recombination. This study shows that visible s-SNOM is capable of profiling the morphological backdrop pertaining to the operation of high performance organic solar cells.

scholarly journals All-small-molecule organic solar cells with over 14% efficiency by optimizing hierarchical morphologies

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ruimin Zhou ◽  
Zhaoyan Jiang ◽  
Chen Yang ◽  
Jianwei Yu ◽  
Jirui Feng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Small Molecule ◽  
Organic Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Bulk Heterojunction ◽  
Photovoltaic Performance ◽  
Photovoltaic System ◽  
Active Layers ◽  
Donor Acceptor

AbstractThe high efficiency all-small-molecule organic solar cells (OSCs) normally require optimized morphology in their bulk heterojunction active layers. Herein, a small-molecule donor is designed and synthesized, and single-crystal structural analyses reveal its explicit molecular planarity and compact intermolecular packing. A promising narrow bandgap small-molecule with absorption edge of more than 930 nm along with our home-designed small molecule is selected as electron acceptors. To the best of our knowledge, the binary all-small-molecule OSCs achieve the highest efficiency of 14.34% by optimizing their hierarchical morphologies, in which the donor or acceptor rich domains with size up to ca. 70 nm, and the donor crystals of tens of nanometers, together with the donor-acceptor blending, are proved coexisting in the hierarchical large domain. All-small-molecule photovoltaic system shows its promising for high performance OSCs, and our study is likely to lead to insights in relations between bulk heterojunction structure and photovoltaic performance.

scholarly journals Pseudo-bilayer architecture enables high-performance organic solar cells with enhanced exciton diffusion length

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kui Jiang ◽  
Jie Zhang ◽  
Zhengxing Peng ◽  
Francis Lin ◽  
Shengfan Wu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Active Layer ◽  
Organic Solar Cells ◽  
High Performance ◽  
Diffusion Length ◽  
Bulk Heterojunction ◽  
Short Circuit ◽  
Full Potential ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length

AbstractSolution-processed organic solar cells (OSCs) are a promising candidate for next-generation photovoltaic technologies. However, the short exciton diffusion length of the bulk heterojunction active layer in OSCs strongly hampers the full potential to be realized in these bulk heterojunction OSCs. Herein, we report high-performance OSCs with a pseudo-bilayer architecture, which possesses longer exciton diffusion length benefited from higher film crystallinity. This feature ensures the synergistic advantages of efficient exciton dissociation and charge transport in OSCs with pseudo-bilayer architecture, enabling a higher power conversion efficiency (17.42%) to be achieved compared to those with bulk heterojunction architecture (16.44%) due to higher short-circuit current density and fill factor. A certified efficiency of 16.31% is also achieved for the ternary OSC with a pseudo-bilayer active layer. Our results demonstrate the excellent potential for pseudo-bilayer architecture to be used for future OSC applications.

Theoretical study on mesoscopic-size impurity effects in the charge separation process of organic photocells

2018 ◽  
Vol 20 (21) ◽  
pp. 14846-14854
Author(s):  
Tomomi Shimazaki ◽  
Motomichi Tashiro ◽  
Takahito Nakajima
Keyword(s):  
Charge Separation ◽  
High Performance ◽  
Theoretical Study ◽  
Bulk Heterojunction ◽  
Separation Process ◽  
Impurity Effects ◽  
Heterojunction Structure ◽  
Donor And Acceptor

A bulk-heterojunction structure is often employed to develop high-performance organic photocells, in which the donor and acceptor regions are complexly intertwined.

scholarly journals Selective Extraction of Nonfullerene Acceptors from Bulk-Heterojunction Layer in Organic Solar Cells for Detailed Analysis of Microstructure

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2107
Author(s):  
Masahiro Nakano ◽  
Akira Takahara ◽  
Kenji Genda ◽  
Md. Shahiduzzaman ◽  
Makoto Karakawa ◽  
...  
Keyword(s):  
Solar Cells ◽  
Detailed Analysis ◽  
Organic Solar Cells ◽  
High Performance ◽  
Bulk Heterojunction ◽  
Glycidyl Ether ◽  
Complex Mixture ◽  
Selective Extraction ◽  
Donor And Acceptor ◽  
Butyl Glycidyl Ether

Detailed analyses of the microstructures of bulk-heterojunction (BHJ) layers are important for the development of high-performance photovoltaic organic solar cells (OSCs). However, analytical methods for BHJ layer microstructures are limited because BHJ films are composed of a complex mixture of donor and acceptor materials. In our previous study on the microstructure of a BHJ film composed of donor polymers and fullerene-based acceptors, we analyzed donor polymer-only films after selectively extracting fullerene-based acceptors from the film by atomic force microscopy (AFM). Not only was AFM suitable for a clear analysis of the morphology of the donor polymers in the BHJ film, but it also allowed us to approximate the acceptor morphology by analyzing the pores in the extracted films. Herein we report a method for the selective extraction of nonfullerene acceptors (NFAs) from a BHJ layer in OSCs and provide a detailed analysis of the remaining BHJ films based upon AFM. We found that butyl glycidyl ether is an effective solvent to extract NFAs from BHJ films without damaging the donor polymer films. By using the selective extraction method, the morphologies of NFA-free BHJ films fabricated under various conditions were studied in detail. The results may be useful for the optimization of BHJ film structures composed of NFAs and donor polymers.

The Effect of Donor:Acceptor Ratio on the Generated Photocurrent of Inkjet Printed Blended Poly (3-Octylthiophene-2.5-Diyl) and (6,6)-Phenyl C71 Butyric Acid Methyl Ester Bulk Heterojunction Organic Solar Cells

2010 ◽  
Vol 663-665 ◽  
pp. 823-827 ◽  
Author(s):  
Vivi Fauzia ◽  
Akrajas Ali Umar ◽  
Muhamad Mat Salleh ◽  
Muhammad Yahaya
Keyword(s):  
Solar Cells ◽  
Methyl Ester ◽  
Butyric Acid ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Photovoltaic Performance ◽  
Acid Methyl Ester ◽  
Acid Methyl ◽  
Donor And Acceptor ◽  
Butyric Acid Methyl Ester

Bulk heterojunction organic solar cells made of blended of the electron donor (D) and electron acceptor (A) molecules were fabricated using inkjet printing technique with three different D:A ratios i.e. 1:3, 1:1 and 3:1 (weight). Poly (3-octylthiophene-2,5-diyl) (P3OT) and (6,6)-phenyl C71 butyric acid methyl ester (PC71BM) were used as donor and acceptor respectively. The generated photocurrents and the power conversion efficiency depend on the donor: acceptor ratio, where the device D:A ratio 3:1 generated higher photocurrent. The photovoltaic performance of the devices may also affected by the microstructure and surface morphology of the active layer film.

New solution processed bulk-heterojunction organic solar cells based on a triazine-bridged porphyrin dyad as electron donor

RSC Advances ◽  
2014 ◽  
Vol 4 (92) ◽  
pp. 50819-50827 ◽  
Author(s):  
Ganesh D. Sharma ◽  
Galateia E. Zervaki ◽  
Panagiotis Angaridis ◽  
Athanassios G. Coutsolelos
Keyword(s):  
Solar Cells ◽  
Active Layer ◽  
Electron Donor ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Solution Processed ◽  
Zinc Porphyrin ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor ◽  
Covalently Linked

An unsymmetrical porphyrin dyad (ZnP)-[triazine-Npip]-(ZnPCOOH) consisting of two zinc-porphyrin units covalently linked to a peridine-containing triazine group has been used with PC71BM as electron donor and acceptor, respectively, for the active layer of solution-processed BHJ organic solar cells.

scholarly journals Characterising Exciton Generation in Bulk-Heterojunction Organic Solar Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 209
Author(s):  
Kiran Sreedhar Ram ◽  
Hooman Mehdizadeh-Rad ◽  
David Ompong ◽  
Daniel Setsoafia ◽  
Jai Singh
Keyword(s):  
Solar Cells ◽  
Electric Fields ◽  
Active Layer ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Short Circuit Current ◽  
Photon Absorption ◽  
Active Layer Thickness

In this paper, characterisation of exciton generation is carried out in three bulk-heterojunction organic solar cells (BHJ OSCs)—OSC1: an inverted non-fullerene (NF) BHJ OSC; OSC2: a conventional NF BHJ OSC; and OSC3: a conventional fullerene BHJ OSC. It is found that the overlap of the regions of strong constructive interference of incident and reflected electric fields of electromagnetic waves and those of high photon absorption within the active layer depends on the active layer thickness. An optimal thickness of the active layer can thus be obtained at which this overlap is maximum. We have simulated the rates of total exciton generation and position dependent exciton generation within the active layer as a function of the thicknesses of all the layers in all three OSCs and optimised their structures. Based on our simulated results, the inverted NF BHJ OSC1 is found to have better short circuit current density which may lead to better photovoltaic performance than the other two. It is expected that the results of this paper may provide guidance in fabricating highly efficient and cost effective BHJ OSCs.

Interfacial Energy Alignment at the ITO/Ultra-Thin Electron Selective Dielectric Layer Interface and Its Effect on the Efficiency of Bulk-Heterojunction Organic Solar Cells

2016 ◽  
Vol 16 (4) ◽  
pp. 3248-3253 ◽  
Author(s):  
Eiji Itoh ◽  
Yoshinori Goto ◽  
Yusuke Saka ◽  
Katsutoshi Fukuda
Keyword(s):  
Contact Resistance ◽  
Active Layer ◽  
Surface Potential ◽  
Organic Solar Cells ◽  
Indium Tin Oxide ◽  
Bulk Heterojunction ◽  
Electronic Charge ◽  
Photovoltaic Properties ◽  
Potential Measurement ◽  
Layer Interface

We have investigated the photovoltaic properties of an inverted bulk heterojunction (BHJ) cell in a device with an indium-tin-oxide (ITO)/electron selective layer (ESL)/P3HT:PCBM active layer/MoOx/Ag multilayered structure. The insertion of only single layer of poly(diallyl-dimethylammonium chloride) (PDDA) cationic polymer film (or poly(ethyleneimine) (PEI) polymeric interfacial dipole layer) and titanium oxide nanosheet (TN) films as an ESL effectively improved cell performance. Abnormal S-shaped curves were observed in the inverted BHJ cells owing to the contact resistance across the ITO/active layer interface and the ITO/PDDA/TN/active layer interface. The series resistance across the ITO/ESL interface in the inverted BHJ cell was successfully reduced using an interfacial layer with a positively charged surface potential with respect to ITO base electrode. The positive dipole in PEI and the electronic charge phenomena at the electrophoretic deposited TN (ED-TN) films on ITO contributed to the reduction of the contact resistance at the electrode interface. The surface potential measurement revealed that the energy alignment by the transfer of electronic charges from the ED-TN to the base electrodes. The insertion of the ESL with a large positive surface potential reduced the potential barrier for the electron injection at ITO/TN interface and it improved the photovoltaic properties of the inverted cell with an ITO/TN/active layer/MoOx/Ag structure.

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