Crystallinity and Molecular Packing of Small Molecules in Bulk-Heterojunction Organic Solar Cells
Source abstract
Abstract
Crystallinity has played a major role in organic solar cells (OSCs). In small molecule (SM) bulk-heterojunction (BHJ) OSCs, the crystallinity and crystalline packing of SM donors have been shown to have a dramatic impact on the formation of an optimum microstructure leading to high-power conversion efficiency (PCE). Herein we describe how crystallinity differs from polymers to SMs, and how the packing habits of SMs (particularly donors) in active layers of BHJ devices can be described as following two different main modes: a single crystal-like and a liquid crystal-like packing type. This notion is reviewed from a chronological perspective, emphasising milestone donor structures and studies focusing on the crystallinity in SM-BHJ OSCs. This review intends to demonstrate that a shift towards a liquid crystalline-like packing can be identified throughout the history of SM-BHJ, and that this shift can be associated with an increase in overall PCE.
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Research context
OpenAlex topics: Organic Electronics and Photovoltaics · Conducting polymers and applications · Perovskite Materials and Applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
The Institute of Analytical Sciences and Physico-Chemistry for Environment and Materials (IPREM), Technopole Hélioparc, 2 Avenue du Président Pierre Angot, CEDEX 09, 64053 Pau, France
Funding
E2S UPPA
References (88)
Show source-provided references
1. Two-layer Organic Photovoltaic Cell10.1063/1.96937 ↗
2. Rand, B.P., and Richter, H. (2014). Organic Solar Cells: Fundamentals, Devices, and Upscaling, Jenny Stanford Publishing.10.1201/b17301 ↗
3. Yang, Y., and Li, G. (2015). Progress in High-Efficient Solution Process Organic Photovoltaic Devices, Springer. Topics in Applied Physics.10.1007/978-3-662-45509-8 ↗
4. Microstructural Characterization and Charge Transport in Thin Films of Conjugated Polymers10.1002/adma.200903712 ↗
5. Molecular Characterization of Organic Electronic Films10.1002/adma.201001760 ↗
6. Morphological Characterization of Fullerene and Fullerene-Free Organic Photovoltaics by Combined Real and Reciprocal Space Techniques10.1557/jmr.2017.131 ↗
7. Morphology Characterization in Organic and Hybrid Solar Cells10.1039/c2ee22056c ↗
8. Morphology Control in Organic Solar Cells10.1002/aenm.201703147 ↗
9. Morphology Development in Solution-Processed Functional Organic Blend Films: An In Situ Viewpoint10.1021/acs.chemrev.6b00618 ↗
10. Morphology of Organic Photovoltaic Non-Fullerene Acceptors Investigated by Grazing Incidence X-ray Scattering Techniques10.1016/j.mtnano.2019.100030 ↗
11. Charge Transport in Organic Semiconductors10.1021/cr050140x ↗
12. Molecular Understanding of Organic Solar Cells: The Challenges10.1021/ar900099h ↗
13. Organic Photovoltaics10.1039/b812502n ↗
14. Charge Photogeneration in Organic Solar Cells10.1021/cr900271s ↗
15. Thin Film Growth Studies Using Time-Resolved x-Ray Scattering10.1088/1361-648X/29/4/043003 ↗
16. On the Morphology of Polymer-Based Photovoltaics10.1002/polb.23063 ↗
17. Metal Phthalocyanines: Thin-Film Formation, Microstructure, and Physical Properties10.1039/D1RA03853B ↗
18. Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells10.3390/polym7020333 ↗
19. Growth and Degradation Kinetics of Organic-Inorganic Hybrid Perovskite Films Determined by In Situ Grazing-Incidence X-ray Scattering Techniques10.1002/smtd.202100829 ↗
20. Delicate Morphology Control Triggers 14.7% Efficiency All-Small-Molecule Organic Solar Cells10.1002/aenm.202001076 ↗
21. Extensive Studies on π-Stacking of Poly(3-Alkylthiophene-2,5-Diyl)s and Poly(4-Alkylthiazole-2,5-Diyl)s by Optical Spectroscopy, NMR Analysis, Light Scattering Analysis, and X-Ray Crystallography10.1021/ja973873a ↗
22. Morphology of P3HT in Thin Films in Relation to Optical and Electrical Properties10.1007/12_2014_288 ↗
23. P3HT/PCBM Bulk Heterojunction Solar Cells: Relation between Morphology and Electro-Optical Characteristics10.1016/j.solmat.2006.02.010 ↗
24. Influence of Nanomorphology on the Photovoltaic Action of Polymer–Fullerene Composites10.1088/0957-4484/15/9/035 ↗
25. Effects of Postproduction Treatment on Plastic Solar Cells10.1002/adfm.200390011 ↗
26. Correlation Between Structural and Optical Properties of Composite Polymer/Fullerene Films for Organic Solar Cells10.1002/adfm.200400521 ↗
27. Composition and Annealing Effects in Polythiophene/Fullerene Solar Cells10.1007/s10853-005-0568-0 ↗
28. Effect of Polymer Crystallinity in P3HT:PCBM Solar Cells on Band Gap Trap States and Apparent Recombination Order10.1002/aenm.201200674 ↗
29. Solid Mesophases in Semicrystalline Polymers: Structural Analysis by DiffractionTechniques10.1007/b107169 ↗
30. Blinov, L.M. (2011). Structure and Properties of Liquid Crystals, Springer.10.1007/978-90-481-8829-1 ↗
31. Hammond, C. (2015). The Basics of Crystallography and Diffraction, Oxford University Press. [4th ed.]. International Union of Crystallography Texts on Crystallography.10.1093/acprof:oso/9780198738671.001.0001 ↗
32. Guinebretiere, R. (2007). X-ray Diffraction by Polycrystalline Materials, ISTE.10.1002/9780470612408 ↗
33. A Review of Grazing Incidence Small- and Wide-Angle X-Ray Scattering Techniques for Exploring the Film Morphology of Organic Solar Cells10.1002/solr.202000337 ↗
34. Quantitative Determination of Organic Semiconductor Microstructure from the Molecular to Device Scale10.1021/cr3001109 ↗
35. Investigation of Morphological Degradation of P3HT:PCBM Bulk Heterojunction Films Exposed to Long-Term Host Solvent Vapor10.1039/C5TA09873D ↗
36. Side-Chain Engineering of Nonfullerene Acceptors for Near-Infrared Organic Photodetectors and Photovoltaics10.1021/acsenergylett.9b00721 ↗
37. Molecular Materials for Organic Photovoltaics: Small Is Beautiful10.1002/adma.201305999 ↗
38. Porphyrin-Based Bulk Heterojunction Organic Photovoltaics: The Rise of the Colors of Life10.1002/aenm.201500218 ↗
39. Small Molecule Solution-Processed Bulk Heterojunction Solar Cells10.1021/cm102189g ↗
40. Small-Molecule Solar Cells—Status and Perspectives10.1088/0957-4484/19/42/424001 ↗
41. High Performance Photovoltaic Applications Using Solution-Processed Small Molecules10.1021/ar400088c ↗
42. Dicyanovinylene-Substituted Oligothiophenes for Organic Solar Cells10.1007/978-3-319-28338-8_3 ↗
43. Benzo[1,2-b:4,5-B′]Dithiophene (BDT)-Based Small Molecules for Solution Processed Organic Solar Cells10.1039/C4TA06452F ↗
44. Thiophene-Based Push–Pull Chromophores for Small Molecule Organic Solar Cells (SMOSCs)10.1039/C4RA11664J ↗
45. Photo-Induced Charge Carrier Recombination Kinetics in Small Molecule Organic Solar Cells and the Influence of Film Nanomorphology10.1002/aenm.201601509 ↗
46. A-π-D-π-A Electron-Donating Small Molecules for Solution-Processed Organic Solar Cells: A Review10.1002/marc.201700470 ↗
47. Benzodithiophene-Based Small-Molecule Donors for Next-Generation All-Small-Molecule Organic Photovoltaics10.1016/j.matt.2020.09.001 ↗
48. Design and Synthesis of Molecular Donors for Solution-Processed High-Efficiency Organic Solar Cells10.1021/ar400136b ↗
49. Chen, H., Tang, H., Hu, D., Xiao, Y., Fu, J., Lv, J., Yu, Q., Xiao, Z., Lu, X., and Hu, H. (2021). Design of All-Small-Molecule Organic Solar Cells Approaching 14% Efficiency via Isometric Terminal Alkyl Chain Engineering. Energies, 14.10.3390/en14092505 ↗
50. Design Principles and Synergistic Effects of Chlorination on a Conjugated Backbone for Efficient Organic Photovoltaics: A Critical Review10.1002/adma.201906175 ↗
51. High Efficiency Small Molecule-Based Donor Materials for Organic Solar Cells10.1016/j.orgel.2018.03.048 ↗
52. Recent Progress on all-small Molecule Organic Solar Cells Using small-molecule Nonfullerene Acceptors10.1002/inf2.12163 ↗
53. Small Is Powerful: Recent Progress in Solution-Processed Small Molecule Solar Cells10.1002/aenm.201602242 ↗
54. Solution Processed Organic Solar Cells Based on A–D–D′–D–A Small Molecule with Benzo[1,2-b:4,5-B′]Dithiophene Donor (D′) Unit, Cyclopentadithiophene Donor (D) and Ethylrhodanine Acceptor Unit Having 6% Light to Energy Conversion Efficiency10.1039/C4TA05807K ↗
55. Solvent Annealing Control of Bulk Heterojunction Organic Solar Cells with 6.6% Efficiency Based on a Benzodithiophene Donor Core and Dicyano Acceptor Units10.1021/acs.jpcc.5b07130 ↗
56. High Open Circuit Voltage in Efficient Thiophene-Based Small Molecule Solution Processed Organic Solar Cells10.1016/j.orgel.2013.08.004 ↗
57. Formation of Highly Crystalline and Texturized Donor Domains in DPP(TBFu)2:PC71BM SM-BHJ Devices via Solvent Vapour Annealing: Implications for Device Function10.1039/c2jm31235b ↗
58. Effects of Stereoisomerism on the Crystallization Behavior and Optoelectrical Properties of Conjugated Molecules10.1002/adma.201300255 ↗
59. Influence of Structural Variation on the Solid-State Properties of Diketopyrrolopyrrole-Based Oligophenylenethiophenes: Single-Crystal Structures, Thermal Properties, Optical Bandgaps, Energy Levels, Film Morphology, and Hole Mobility10.1021/cm202852f ↗
60. Interrelation between Crystal Packing and Small-Molecule Organic Solar Cell Performance10.1002/adma.201104439 ↗
61. Solvent-Annealed Crystalline Squaraine: PC70BM (1:6) Solar Cells10.1002/aenm.201100045 ↗
62. Solution-Processed Squaraine Bulk Heterojunction Photovoltaic Cells10.1021/nn100195j ↗
63. Unambiguous Determination of Molecular Packing in Crystalline Donor Domains of Small Molecule Solution Processed Solar Cell Devices Using Routine X-Ray Diffraction Techniques10.1039/c3ta13116e ↗
64. Understanding the Limiting Factors of Solvent-Annealed Small-Molecule Bulk-Heterojunction Organic Solar Cells from a Chemical Perspective10.1002/cssc.201700440 ↗
65. (2022, March 30). Kinetics of Materials | Wiley. Available online: https://www.wiley.com/en-us/Kinetics+of+Materials-p-9780471246893.
66. A Novel Acceptor with a N,N-Dialkyl Thieno[3′,2′:2,3]Indolo[7,6-g ]Thieno[3,2-b]Indole (TITI) Core for Organic Solar Cells with a High Fill Factor of 0.7510.1039/C9CC08098H ↗
67. A Series of Simple Oligomer-like Small Molecules Based on Oligothiophenes for Solution-Processed Solar Cells with High Efficiency10.1021/jacs.5b00305 ↗
68. A Solution-Processed High Performance Organic Solar Cell Using a Small Molecule with the Thieno[3,2-b]Thiophene Central Unit10.1039/C5CC06009E ↗
69. Small-Molecule Solar Cells with Efficiency over 9%10.1038/nphoton.2014.269 ↗
70. Solution-Processed Organic Solar Cells Based on Dialkylthiol-Substituted Benzodithiophene Unit with Efficiency near 10%10.1021/ja509703k ↗
71. A Planar Small Molecule with Dithienosilole Core for High Efficiency Solution-Processed Organic Photovoltaic Cells10.1021/cm202588h ↗
72. Dithienogermole-Based Solution-Processed Molecular Solar Cells with Efficiency over 9%10.1039/C6CC03998G ↗
73. Film Morphology of High Efficiency Solution-Processed Small-Molecule Solar Cells10.1002/adfm.201300099 ↗
74. Intensity Dependence of Current–Voltage Characteristics and Recombination in High-Efficiency Solution-Processed Small-Molecule Solar Cells10.1021/nn401267s ↗
75. Significance of Average Domain Purity and Mixed Domains on the Photovoltaic Performance of High-Efficiency Solution-Processed Small-Molecule BHJ Solar Cells10.1002/aenm.201500877 ↗
76. Solution-Processed Small-Molecule Solar Cells with 6.7% Efficiency10.1038/nmat3160 ↗
77. Solvent Additive Effects on Small Molecule Crystallization in Bulk Heterojunction Solar Cells Probed During Spin Casting10.1002/adma.201302389 ↗
78. Toward Additive-Free Small-Molecule Organic Solar Cells: Roles of the Donor Crystallization Pathway and Dynamics10.1002/adma.201503395 ↗
79. Effects of Alkyl Terminal Chains on Morphology, Charge Generation, Transport, and Recombination Mechanisms in Solution-Processed Small Molecule Bulk Heterojunction Solar Cells10.1002/aenm.201500386 ↗
80. High-Molecular-Weight Insulating Polymers Can Improve the Performance of Molecular Solar Cells10.1002/adma.201400497 ↗
81. 14.46% Efficiency Small Molecule Organic Photovoltaics Enabled by the Well Trade-off between Phase Separation and Photon Harvesting10.1016/j.jechem.2020.09.025 ↗
82. A Molecular Nematic Liquid Crystalline Material for High-Performance Organic Photovoltaics10.1038/ncomms7013 ↗
83. All-Small-Molecule Organic Solar Cells with an Ordered Liquid Crystalline Donor10.1016/j.joule.2019.09.009 ↗
84. Effect of Side-Chain Modification on the Active Layer Morphology and Photovoltaic Performance of Liquid Crystalline Molecular Materials10.1021/acsami.0c20389 ↗
85. Morphology Evolution Induced by Sequential Annealing Enabling Enhanced Efficiency in All-Small Molecule Solar Cells10.1021/acsaem.1c00617 ↗
86. Spatially Orthogonal 2D Sidechains Optimize Morphology in All-Small-Molecule Organic Solar Cells10.1002/adfm.202100750 ↗
87. Small Molecules Based on Benzo[1,2-b:4,5-B′]Dithiophene Unit for High-Performance Solution-Processed Organic Solar Cells10.1021/ja306865z ↗
88. Solution-Processed and High-Performance Organic Solar Cells Using Small Molecules with a Benzodithiophene Unit10.1021/ja403318y ↗