An Amidine‐Type n‐Dopant for Solution‐Processed Field‐Effect Transistors and Perovskite Solar Cells

Hu, Lin; Liu, Tiefeng; Duan, Jiashun; Ma, Xiaoyi; Ge, Congwu; Jiang, Youyu; Qin, Fei; Xiong, Sixing; Jiang, Fangyuan; Hu, Bin; Gao, Xike; Yi, Yuanping; Zhou, Yinhua

doi:10.1002/adfm.201703254

Cited by 41 publications

(35 citation statements)

References 32 publications

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“…Full mitigation of s-shapes was achieved by adjusting the contacts, such as by using a different work function material [110] or by doping the contact layer [58]. Improvements of the FF without fully mitigating the s-shape was achieved by doping either absorber [44], [132] or selective contact materials [131]. Furthermore, decreasing the thickness of passivating [30], charge blocking [100], or buffer layers has been shown to mitigate s-shape I-V curves.…”

Section: Discussionmentioning

confidence: 99%

S-Shaped Current–Voltage Characteristics in Solar Cells: A Review

Saive

2019

IEEE J. Photovoltaics

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S-shaped current-voltage (I-V) characteristics are a frequently occurring hurdle in the development of new solar cell material combinations and device architectures. Their presence points to the existence of a charge transport bottleneck that needs to be removed in order to unlock high fill factors and power conversion efficiencies. In this review, examples of studies in which s-shaped I-V curves have appeared are presented, and the cause and mitigation are discussed. Different solar cell material systems are often treated by separate communities, thereby, also the physics of s-shaped I-V curves have been treated separately. This review covers the main solar cell technologies-silicon, thin film, organic, hybrid-with the aim to provide an overarching picture of the common mechanisms and universal guidelines for mitigation of s-shaped I-V characteristics in emerging solar cell technologies. Except for a few studies on organic solar cells, s-shaped I-V curves are reported to result from charge transport barriers at one of the (selective) contact layers that can be overcome by interface engineering and doping.Index Terms-Current-voltage characteristics, s-shape, roll over.

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Section: Discussionmentioning

confidence: 99%

S-Shaped Current–Voltage Characteristics in Solar Cells: A Review

Saive

2019

IEEE J. Photovoltaics

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“…[232][233][234][235][236] Although, these materials have improved the performance of devices but they suffer from some critical issues. [237][238][239] Apart from metals, some metal oxides are often used because they can also be used to block the holes and to serve as self-encapsulation layer.…”

Section: Advantages Of Zwitterion Interlayer Materialsmentioning

confidence: 99%

Zwitterions for Organic/Perovskite Solar Cells, Light‐Emitting Devices, and Lithium Ion Batteries: Recent Progress and Perspectives

Islam

Pervaiz

et al. 2019

Advanced Energy Materials

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are covalently bonded and their unique characteristics enable them to demonstrate special performance in applications and distinguish them from other conventional organic salts. [12][13][14] Recently, a significant attention has been paid to the use of zwitterions owing to their solubility in polar solvents for solution processing, [15][16][17] and dipole formation for the transfer of carriers [18][19][20] and ions. [21][22][23] Zwitterions have emerged as alternatives to the widely used building blocks such as conventional ionic groups, for developing new functional materials. The presence of both negative and positive ions in the same molecule enables zwitterions to develop interfacial dipole. The ability of zwitterions to develop interfacial dipole provides a new pathway to utilize them as interfacial layer in optoelectronic devices, including organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting devices (OLEDs), as well as electrolyte additives for energy devices such as lithium ion batteries (LIBs).It is well known that the ability to transport the charge carriers between the electrodes and organic layers is very crucial to obtain highly efficient electronic devices. [24] A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers. [25] To get rid of this obstacle, an interlayer between the electrodes and organic layers is applied to facilitate the transfer of charges in organic devices. In OLEDs, interlayers are used to enhance charge injection and reduce the height of Schottky barrier. While in the case of OSCs and PVSCs, apart from the enhancement in charge injection, they also play an important role to increase the built-in electric field across the active layer, ensuring efficient extraction of photogenerated charge carriers. [26][27][28][29][30] Therefore, the design and development of effective interlayer materials for interfacial modification are crucial for high-performance electronic devices. Recently, some significant advances have been demonstrated by applying an interfacial layer between the electrodes and organic layers, resulting in power conversion efficiencies (PCEs) to exceed 14% for single-junction OSCs by choosing appropriate photoactive layer. [31,32] Among different interlayer materials used so far, zwitterionic materials have been proved Zwitterions, a class of materials that contain covalently bonded cations and anions, have been extensively studied in the past decades owing to their special features, such as excellent solubility in polar solvents, for solution processing and dipole formation for the transfer of carriers and ions. Recently, zwitterions have been developed as electrode modifiers for organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting devices (OLEDs), as well as electrolyte additives for lithium ion batteries (LIBs).With the rapid advances of zwitterionic materials, high-performan...

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“…However, at a high doping concentration, usually large OFF currents are induced in unipolar OSCs, degrading the device performance . Recently, Hu et al reported the use of a low‐cost effective amidine‐type n‐dopant, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), to dope electron‐rich OSCs. This doping worked well in both solar cells and FETs.…”

Section: Binary Interfaces In Functional Devicesmentioning

confidence: 99%

Precise Control of Interfacial Charge Transport for Building Functional Optoelectronic Devices

Zhang

Chen

Guo

2019

Adv Materials Technologies

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studies have not only improved device performance, but have even built novel functions. At present, interface engineering has become a research hotspot and has great potential for further applications in diverse fields, ranging from integrated circuits and energy conversion to catalysis and chemical/biosensors. Scientists with various backgrounds have been devoting great efforts to this area, which has moved from the simple improvement of device performance to branch out in broad directions, indicating its interdisciplinarity.As shown in Figure 1c, an important interface for an FET is the semiconductor/ electrode interface, which typically determines the efficiency of charge carrier injection and extraction. In general, the charge injection of a metal/organic semiconductor (OSC) junction can be described in terms of thermal electron emission or tunneling mechanisms, depending on the concentration of defect states inside the bandgap (Figure 1c, left and middle). [1] By carefully selecting the self-assembled monolayer (SAM) or thin buffer interlayer to modify the metal electrode (Figure 1c, right), the interface charge injection barrier can be fine-tuned, thereby significantly reducing the contact resistance of the device. More interestingly, by using a stimuli-responsive conformational isomer as a functional layer to modify the electrode interface, functionalization of the electrodes can be achieved. This concept laid the foundation for the construction of functional devices such as optical/electrical switches, memory, and photodetectors.The semiconductor/dielectric interface is another important interface in FETs, that governs carrier transport (Figure 1d, left), because generation, transport, and regulation of charge carriers all occur in the first few layers (<10 nm) of semiconductors at the interface (Figure 1d, middle). In addition, the modification of the dielectric surface has been shown to help reduce the defects, improve the roughness, change the polarity, and modulate the surface hydrophilic/hydrophobic properties. These changes further affect the transport of carriers at the semiconductor/dielectric interface (Figure 1d, right) and have a significant impact on the morphology of the semiconductor layer. Furthermore, modification of the interface with SAMs or stimuli-responsive layers offers an important and general methodology to improve device performance and even integrate new molecular functionalities, such as photocontrollable memory, superconductivity, and charge-trap memory, into organic electrical circuits. Optoelectronic devices and interfaces therein have captured great attention in both scientific and industrial communities because of the wide variety of their unique properties. From a materials chemistry point of view, each layer and individual component of an optoelectronic device possesses the possibility of flexible chemical modification, making it feasible to dope, mix, and physically/chemically modify the interface. Exploiting the novel properties in optoelectronic devices with diverse la...

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An Amidine‐Type n‐Dopant for Solution‐Processed Field‐Effect Transistors and Perovskite Solar Cells

Cited by 41 publications

References 32 publications

S-Shaped Current–Voltage Characteristics in Solar Cells: A Review

S-Shaped Current–Voltage Characteristics in Solar Cells: A Review

Zwitterions for Organic/Perovskite Solar Cells, Light‐Emitting Devices, and Lithium Ion Batteries: Recent Progress and Perspectives

Precise Control of Interfacial Charge Transport for Building Functional Optoelectronic Devices

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