Configuration dependent photovoltaic properties of cyclometalated heavy metal complexes for organic solar cells

Yang, Tianjian; Zhou, Aihua; He, Yinming; Yao, Zhichao; Song, Xiaochen; Tao, Xianwang; Tao, Youtian

doi:10.1039/d2ma00999d

Cited by 4 publications

(8 citation statements)

References 50 publications

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“…[46] Studies revealed that exciton diffusion length can be increased by use of donor or acceptor materials which contain heavy atoms that permit intersystem crossing and by doping active layer with triple sensitizers. [47] Yang et al [48] investigated electron donor materials of 2-(5 00 -tert-butyl-[2,2 0 :5 0 ,2 00 -terthiophen]-5-yl)benzo [d]thiazole (tTBz) ligand, platinum (II) complex (tTBzPt), octahedral homoleptic iridium (III) complex (tTBz3Ir), and octahedral heteroleptic tTBzIr complex for OPVs. The molecular geometries of these donor materials were investigated using density functional theory (see Figure 2B).…”

Section: Exciton Diffusionmentioning

confidence: 99%

Advances in Organic Photovoltaic Cells: Fine‐Tuning of the Photovoltaic Processes

Ramoroka,

Yussuf,

Nwambaekwe

et al. 2024

Solar RRL

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Due to the negative impact and possible run out of fossil fuels, the use of an alternative source of energy, which is plentiful, is crucial. The use of sunlight to produce energy by means of photovoltaic cell devices is the perfect approach to deal with the disadvantages of fossil fuels. Now, the photovoltaics that are already in market because of their power conversion efficiency (PCE) and stability are based on inorganic materials. These inorganic materials are however faced with drawbacks such as toxicity and high fabrication cost. Changing inorganic materials to organic overcome those drawbacks making organic photovoltaic cells (OPVs) of importance. The problem with the OPVs is the low PCE and low stability. For decades now, researchers have been trying to improve the performance of OPVs by modifying active layer materials with the PCE of over 19% reached. This performance was achieved by performing intensive investigations to understand how the materials used in OPVs affect their performance. Our work highlights recent advancements on how the structures and chemical makeups of the active layer materials affects photovoltaic processes and performance in terms of power conversion efficiency and stability. It further sheds lights on the performance optimization of OPV and the relationship between these optimization conditions and OPV performance. The use of different substituents on the same donor or acceptor material has different optimal conditions. Furthermore, we showed how addition of different third components in the active layer have different optimal concentration point. This review also highlights and suggests a possible way to improve stability of OPVs through modification of the active layer. To date, some studies showed that incorporation of third component in the active layer led to over 97% stability after more than 1000 h.This article is protected by copyright. All rights reserved.

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Section: Exciton Diffusionmentioning

confidence: 99%

Advances in Organic Photovoltaic Cells: Fine‐Tuning of the Photovoltaic Processes

Ramoroka,

Yussuf,

Nwambaekwe

et al. 2024

Solar RRL

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“…34 Furthermore, through systematic modification of the ligand conjugation lengths and alternation of intra-ligand charge transfer behavior, as well as optimization of spatial configuration from heteroleptic to homoleptic Ir complexes, the PCE for smallmolecule cyclometalated Ir complexes based electron donor materials could be enhanced from o4% of (TBz) 2 Ir(acac):PC 71 BM to 410% of homoleptic TBz3Ir:Y6 and eTBz3Ir:L8BO. 25,[28][29][30][35][36][37] It has been noted that previous reports for small-molecule Ir complex-based BHJ OSCs were mainly concentrated on the development of new materials, and studies on device engineering have been rarely performed. The only recent example is the introduction of a bilayer device structure to improve the PCE from 3.91% for (TBz) 2 Ir(acac):PC 71 BM BHJ to 6.17% of bilayer PDCBT/(TBz) 2 Ir(acac):PC 71 BM.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Green solvent-processed organic solar cells based on a small-molecule Ir(iii) complex as electron donor materials

You,

Yang,

Tao

et al. 2024

J. Mater. Chem. C

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“…14 ally, organometallic Ir-and Pt-based complexes were incorporated into both fullerene and nonfullerene acceptor OPVs, with improved PCE due to enhanced absorption, extended exciton lifetime, and increased charge transport. 15 Furthermore, tellurophene-based triplet harvesting materials serve as acceptors for OPVs and contribute to an increased PCE because of long exciton lifetime and improved diffusion length. 16 Bi et al demonstrated a reduction of nonradiative recombination loss due to enlarged exciton diffusion length, which led to an improvement in PCE of the OPV.…”

Section: ■ Introductionmentioning

confidence: 99%

“…For example, the phosphorescent sensitizer fac -tris(2-phenylpyridine) iridium [Ir(ppy) 3 ] exhibits long-lifetime triplet states and allows an increase in exciton diffusion length, resulting in ∼80% power conversion efficiency (PCE) improvement compared to control groups . Additionally, organometallic Ir- and Pt-based complexes were incorporated into both fullerene and nonfullerene acceptor OPVs, with improved PCE due to enhanced absorption, extended exciton lifetime, and increased charge transport . Furthermore, tellurophene-based triplet harvesting materials serve as acceptors for OPVs and contribute to an increased PCE because of long exciton lifetime and improved diffusion length .…”

Section: Introductionmentioning

confidence: 99%

Controlling Nonradiative Recombination in an Organic Semiconducting Polymer Donor–Acceptor System Using Organometallic Phosphors

Chong,

Javed,

Harrell

et al. 2024

J. Phys. Chem. C

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Nonradiative recombination in organic semiconducting materials plays a significant role in energy loss pathways in organic solar cells and organic photodetectors. Here, we investigate a bilayer architecture using semiconducting conjugated polymers�poly(9,9-dioctylfluorene) (PFO) as the donor and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as the acceptor�that includes a red-emitting organometallic phosphor to modify nonradiative recombination. Photophysical investigations of the phosphor-doped donor−acceptor system give insight into the behavior of excitons and the subsequent recombination processes that they undergo. Enhancements in the photoluminescence quantum yield of the PFO layer in the presence of the phosphor indicate that nonradiative recombination within the PFO layer is suppressed because of triplet harvesting by the phosphor. However, in the bilayer with F8BT, the quantum yield is reduced because of triplet energy transfer from the phosphor to F8BT. Transient absorption spectroscopy indicates that the addition of the organometallic phosphor shortens the lifetime of excited singlet excitons in PFO, and increases the lifetime of excited singlet excitons in the bilayer. The photovoltaic and photodetector characteristics of devices incorporating the bilayer show an elevated open-circuit voltage and improved responsivity with the addition of the phosphor. These results demonstrate that phosphors can alter the degree to which nonradiative triplet states contribute to energy loss in organic semiconductor bilayers.

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Configuration dependent photovoltaic properties of cyclometalated heavy metal complexes for organic solar cells

Abstract: Cyclometalated heavy metal complexes as a new class of photovoltaic materials have attracted specific attention owing to their triplet feature, which is expected to be beneficial for longer exciton diffusion...

Cited by 4 publications

References 50 publications

Advances in Organic Photovoltaic Cells: Fine‐Tuning of the Photovoltaic Processes

Advances in Organic Photovoltaic Cells: Fine‐Tuning of the Photovoltaic Processes

Green solvent-processed organic solar cells based on a small-molecule Ir(iii) complex as electron donor materials

Controlling Nonradiative Recombination in an Organic Semiconducting Polymer Donor–Acceptor System Using Organometallic Phosphors

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