Bandgap Science for Organic Solar Cells

Controlling the pn-type behavior of a semiconductor such as silicon by adding an extremely small quantity of an impurity (doping) is a central part of inorganic semiconductor electronics since the 20th century. Recent progress in the doping of organic semiconductors strongly suggests the advent of a new era of doped organic semiconductors. Here, the principles and effects of doping at the level of parts per million (ppm) in organic semiconductor films and single crystals are described, including descriptions of complete pn-control, doping sensitization, ppm doping using an extremely low-speed deposition technique reaching 10 nm s , and emerging ppm-level doping effects, such as trap filling, majority carriers, homojunction formation, and decreased mobility, as well as ppm-level doping effects in organic single crystals measured by the Hall effect, which shows a doping efficiency of 24%. The Wannier excitonic doping of organic single crystals possessing band conduction and the defect science of organic single crystals related to carrier trapping and scattering are introduced as a new scientific field. The dawn of organic single-crystal electronics is also discussed.

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Section: Ppm‐level Doping Methodsmentioning

confidence: 99%

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

2018

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“…This special issue consists of 13 papers especially covering many important topics including seven reviews in the field of organic semiconductors; Organic Semiconductors [13,14], material fabrication and properties [15][16][17][18], OFET [19,20], Sensor [19], OLED [21,22], solar Cells [23,24], Transport Property [17], and Bio-organic electronics [25].…”

Section: The Present Issuementioning

confidence: 99%

“…Improvement in the lifetime of organic photovoltaic cells by using MoO3 in conjunction with tris-(8-hydroxyquinoline) aluminum as a cathode buffer layer is analysed [22]. The concept of bandgap science of organic semiconductor films for use in photovoltaic cells, charge control by doping and design of the built-in potential based on precisely-evaluated doping parameters is summarized in the manuscript [23]. The use of electron and hole transport layers in the inverted bulk heterojunction polymer solar cells is the goal of the article [24].…”

Section: The Present Issuementioning

confidence: 99%

Organic Semiconductors: Past, Present and Future

Jacob

2014

Electronics

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Organic electronics, such as displays, photovoltaics and electronics circuits and components, offer several advantages over the conventional inorganic-based electronics because they are inexpensive, flexible, unbreakable, optically transparent, lightweight and have low power consumption. In particular, organic displays exhibit high brightness, fast response time, wide viewing angle, and low operating voltage. [...]

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“…In contrast, a strongly bounded Frenkel type exciton forms after light absorption in organic semiconductors, because they generally have a smaller dielectric constant when compared with that of inorganic semiconductors [2]. The exciton can be separated using the energy offset between the two organic semiconductor materials called donor and acceptor in organic solar cells (OSCs) [2,3]. The question is whether free charge formation is possible in single organic semiconductor material by light absorption, similar to that in inorganic semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Photoconversion Mechanism at the pn-Homojunction Interface in Single Organic Semiconductor

et al. 2020

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Clarifying critical differences in free charge generation and recombination processes between inorganic and organic semiconductors is important for developing efficient organic photoconversion devices such as solar cells (SCs) and photodetector. In this study, we analyzed the dependence of doping concentration on the photoconversion process at the organic pn-homojunction interface in a single organic semiconductor using the temperature dependence of J-V characteristics and energy structure measurements. Even though the organic pn-homojunction SC devices were fabricated using a single host material and the doping technique resembling an inorganic pn-homojunction, the charge generation and recombination mechanisms are similar to that of conventional donor/acceptor (D/A) type organic SCs; that is, the charge separation happens from localized exciton and charge transfer (CT) state being separated by the energy offset between adjacent molecules, and the recombination happens from localized charge carrier at two adjacent molecules. The determining factor for photoconversion processes is the localized nature of charges in organic semiconductors. The results demonstrated that controlling the delocalization of the charges is important to realize efficient organic photoconversion devices.

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Bandgap Science for Organic Solar Cells

Cited by 50 publications

References 54 publications

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

Organic Semiconductors: Past, Present and Future

Photoconversion Mechanism at the pn-Homojunction Interface in Single Organic Semiconductor

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