scholarly journals Long-range exciton diffusion in non-fullerene acceptors and coarse bulk heterojunctions enable highly efficient organic photovoltaics

2020 ◽  
Vol 8 (31) ◽  
pp. 15687-15694
Author(s):  
Muhammad T. Sajjad ◽  
Arvydas Ruseckas ◽  
Lethy Krishnan Jagadamma ◽  
Yiwei Zhang ◽  
Ifor D. W. Samuel
Keyword(s):  
Long Range ◽  
Organic Photovoltaics ◽  
Diffusion Length ◽  
Three Dimensional ◽  
Accurate Estimate ◽  
Bulk Heterojunctions ◽  
Time Resolved ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence measurements provide an accurate estimate of the three-dimensional exciton diffusion length in three ITICs based non-fullerene acceptors (NFAs).

scholarly journals Enhancing Exciton Diffusion Length Provides New Opportunities for Organic Photovoltaics

Matter ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 341-354
Author(s):  
Muhammad T. Sajjad ◽  
Arvydas Ruseckas ◽  
Ifor D.W. Samuel
Keyword(s):  
Organic Photovoltaics ◽  
Diffusion Length ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length

Triplet excitons: improving exciton diffusion length for enhanced organic photovoltaics

2019 ◽  
Vol 7 (6) ◽  
pp. 2445-2463 ◽  
Author(s):  
Bruno T. Luppi ◽  
Darren Majak ◽  
Manisha Gupta ◽  
Eric Rivard ◽  
Karthik Shankar
Keyword(s):  
Solar Cells ◽  
Organic Photovoltaics ◽  
Organic Materials ◽  
Diffusion Length ◽  
Future Research ◽  
Heavy Atoms ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Fundamental Limitation ◽  
Triplet Excitons

Organic materials containing heavy atoms have been used in photovoltaics to overcome a fundamental limitation: short exciton diffusion length (LD). We highlight studies showing increased LD in solar cells using triplet-generating materials and tackle challenges that the field faces with possible avenues for future research.

scholarly journals Engineering the Color and the Donor-Acceptor Behavior in Nanowires: Blend Versus Coaxial Geometry

2020 ◽  
Author(s):  
Mohamed Mbarek ◽  
Kamel Alimi
Keyword(s):  
Thin Film ◽  
Charge Transfer ◽  
Shell Material ◽  
Time Resolved ◽  
Exciton Diffusion ◽  
The Core ◽  
Exciton Diffusion Length ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence ◽  
Thin Film Devices

The blending or the bilayering of two complementary species are the dominant methods for in-solution-processed thin film devices to get a strong donor-acceptor behavior. They propose opposite strategies for the respective arrangement of the two species, a central point for energy and/or charge transfer. In this work, we propose to engineer at the scale of the exciton diffusion length the organization of a donor (poly(vinyl-carbazole), PVK) and an acceptor (poly(para-phenylene-vinylene), PPV) in a nanowire geometry. A two-step template strategy was used to fabricate coaxial nanowires with PPV and PVK, alternatively as the core or the shell material. Their stationary and time-resolved photoluminescence properties were investigated and compared to the case of PVK-PPV blend. Their respective characteristics are direct evidences of the dominant mechanisms responsible for the emission properties.

scholarly journals Simple donor-acceptor molecule with long exciton diffusion length for organic photovoltaics

2018 ◽  
Vol 53 ◽  
pp. 185-190 ◽  
Author(s):  
Oleg V. Kozlov ◽  
Yuriy N. Luponosov ◽  
Alexander N. Solodukhin ◽  
Bruno Flament ◽  
Olivier Douhéret ◽  
...  
Keyword(s):  
Organic Photovoltaics ◽  
Diffusion Length ◽  
Acceptor Molecule ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Donor Acceptor

Determining the exciton diffusion length of copper phthalocyanine in operating planar-heterojunction organic solar cells

2020 ◽  
Vol 89 (3) ◽  
pp. 30201 ◽  
Author(s):  
Xi Guan ◽  
Shiyu Wang ◽  
Wenxing Liu ◽  
Dashan Qin ◽  
Dayan Ban
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Diffusion Length ◽  
Copper Phthalocyanine ◽  
Short Circuit ◽  
Thick Layer ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length

Organic solar cells based on planar copper phthalocyanine (CuPc)/C60 heterojunction have been characterized, in which a 2 nm-thick layer of bathocuproine (BCP) is inserted into the CuPc layer. The thin layer of BCP allows hole current to tunnel it through but blocks the exciton diffusion, thereby altering the steady-state exciton profile in the CuPc zone (zone 1) sandwiched between BCP and C60. The short-circuit current density (JSC) of device is limited by the hole-exciton scattering effect at the BCP/CuPc (zone 1) interface. Based on the variation of JSC with the width of zone 1, the exciton diffusion length of CuPc is deduced to be 12.5–15 nm. The current research provides an easy and helpful method to determine the exciton diffusion lengths of organic electron donors.

scholarly journals Picosecond time-resolved photon antibunching measures nanoscale exciton motion and the true number of chromophores

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gordon J. Hedley ◽  
Tim Schröder ◽  
Florian Steiner ◽  
Theresa Eder ◽  
Felix J. Hofmann ◽  
...  
Keyword(s):  
Rational Design ◽  
Three Dimensional ◽  
Dna Origami ◽  
Fluorescent Nanoparticles ◽  
Time Resolved ◽  
Exciton Diffusion ◽  
Polymer Aggregates ◽  
True Number ◽  
Particle Level ◽  
Photon Antibunching

AbstractThe particle-like nature of light becomes evident in the photon statistics of fluorescence from single quantum systems as photon antibunching. In multichromophoric systems, exciton diffusion and subsequent annihilation occurs. These processes also yield photon antibunching but cannot be interpreted reliably. Here we develop picosecond time-resolved antibunching to identify and decode such processes. We use this method to measure the true number of chromophores on well-defined multichromophoric DNA-origami structures, and precisely determine the distance-dependent rates of annihilation between excitons. Further, this allows us to measure exciton diffusion in mesoscopic H- and J-type conjugated-polymer aggregates. We distinguish between one-dimensional intra-chain and three-dimensional inter-chain exciton diffusion at different times after excitation and determine the disorder-dependent diffusion lengths. Our method provides a powerful lens through which excitons can be studied at the single-particle level, enabling the rational design of improved excitonic probes such as ultra-bright fluorescent nanoparticles and materials for optoelectronic devices.

Vertically Optimized Phase Separation with Improved Exciton Diffusion Enables High-Efficiency Organic Solar Cells with Thick Active Layers

2021 ◽  
Author(s):  
Yanming Sun ◽  
Yunhao Cai ◽  
Qian Li ◽  
Guanyu Lu ◽  
Hwa Sook Ryu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Phase Separation ◽  
Active Layer ◽  
Organic Solar Cells ◽  
High Efficiency ◽  
Diffusion Length ◽  
Active Layer Thickness ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Active Layers

Abstract The development of high-performance organic solar cells (OSCs) with thick active layers is of crucial importance for the roll-to-roll printing of large-area solar panels. Unfortunately, increasing the active layer thickness usually results in a significant reduction in efficiency. Herein, we fabricated efficient thick-film OSCs with an active layer consisting of one polymer donor and two non-fullerene acceptors. The two acceptors were found to possess enlarged exciton diffusion length in the mixed phase, which is beneficial to exciton generation and dissociation. Additionally, layer by layer approach was employed to optimize the vertical phase separation. Benefiting from the synergetic effects of enlarged exciton diffusion length and graded vertical phase separation, a record high efficiency of 17.31% (certified value of 16.9%) was obtained for the 300 nm-thick OSC, with an unprecedented short-circuit current density of 28.36 mA cm−2, and a high fill factor of 73.0%. Moreover, the device with an active layer thickness of 500 nm also shows a record efficiency of 15.21%. This work provides new insights into the fabrication of high-efficiency OSCs with thick active layers.

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