Ultrafast Photodissociation Dynamics of a Hexaarylbiimidazole Derivative with Pyrenyl Groups: Dispersive Reaction from Femtosecond to 10 ns Time Regions

Miyasaka, Hiroshi; Satoh, Yusuke; Ishibashi, Yukihide; Ito, Syoji; Nagasawa, Yutaka; Taniguchi, Seiji; Chosrowjan, Haik; Mataga, Noboru; Kato, Daisuke; Kikuchi, Azusa; Abe, Jiro

doi:10.1021/ja809195s

Cited by 84 publications

(43 citation statements)

References 44 publications

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“…Despite the great progress in increasing the device PCE from initial 3.8% 4 to the most recent 23.3% 5 in just one decade, the commercialization of this technology remains hindered by the stability issues of materials. It has been reported that the perovskites rapidly degrade under increased temperature 6 , oxygen 7 , moisture 8 , and UV light illumination 9 , often due to the structure instability caused by electromigrations 10 , ion migration, 11 and interfacial relationships 12 .…”

Section: Introductionmentioning

confidence: 99%

Atomic scale insights into structure instability and decomposition pathway of methylammonium lead iodide perovskite

et al. 2018

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Organic–inorganic hybrid perovskites are promising candidates for the next-generation solar cells. Many efforts have been made to study their structures in the search for a better mechanistic understanding to guide the materials optimization. Here, we investigate the structure instability of the single-crystalline CH3NH3PbI3 (MAPbI3) film by using transmission electron microscopy. We find that MAPbI3 is very sensitive to the electron beam illumination and rapidly decomposes into the hexagonal PbI2. We propose a decomposition pathway, initiated with the loss of iodine ions, resulting in eventual collapse of perovskite structure and its decomposition into PbI2. These findings impose important question on the interpretation of experimental data based on electron diffraction and highlight the need to circumvent material decomposition in future electron microscopy studies. The structural evolution during decomposition process also sheds light on the structure instability of organic–inorganic hybrid perovskites in solar cell applications.

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Section: Introductionmentioning

confidence: 99%

Atomic scale insights into structure instability and decomposition pathway of methylammonium lead iodide perovskite

et al. 2018

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“…While PDPP4T is known as a semiconducting D–A polymer with high thin film charge mobility, the selection of the HABI compound is based on the following considerations: i) HABI can be fragmented into a pair of 2,4,5‐triphenylimidazolyl radicals (TPIRs) upon interactions with external stimuli such as light irradiation, and such radical pair can thermally recombine to regenerate HABI . In fact, Abe and others have intensively investigated the photochromic behaviors of HABI derivatives with widely tunable absorptions and fast responsiveness; ii) TPIRs like other organic radicals are expected to have high singly occupied molecular orbital (SOMO) levels, and as a result charge doping or formation of charge‐transfer complexes with the semiconducting polymer or interactions with charge defects at the gate dielectric‐semiconductor interface and within the semiconducting thin film are likely to occur according to previous studies . Therefore, the semiconducting performances of the transistors can be tuned accompanying the formation and recombination of the radical pairs of HABI.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the semiconducting performances of the transistors can be tuned accompanying the formation and recombination of the radical pairs of HABI. However, TPIRs are thermodynamically unstable and they rapidly recombine to form the respective HABIs 18d. Thus, we have to design and synthesize new HABI compounds to enhance the stability of the respective TPIRs.…”

Section: Methodsmentioning

confidence: 99%

Photo‐/Thermal‐Responsive Field‐Effect Transistor upon Blending Polymeric Semiconductor with Hexaarylbiimidazole toward Photonically Programmable and Thermally Erasable Memory Device

et al. 2019

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The past decades have witnessed the rapid development of organic and polymeric semiconductors with high charge mobilities, [1][2][3][4] thanks to the design and synthesis of various conjugated molecules and macromolecules along with the manipulation of self-assembly and interfacial structures. Performances for both p-channel and n-channel field-effect transistors (FETs) are now comparable to and even higher than those of traditional amorphous silicon FETs. Moreover, the promising applications of organic and polymeric semiconductors in low-cost logic circuits (e.g., radio frequency identification tags) and flexible electronics have been successfully demonstrated. [5] New conjugated molecules and macromolecules are being continuously explored for boosting the performances of FETs. Meanwhile, stimuli-responsive organic semiconducting materials, for which the semiconducting properties can be tuned by external stimuli other than electrical fields such as light irradiation and heating, have received increasing attentions in recent years. [6][7][8][9][10][11] This is because multifunctional devices can be constructed with such stimuli-responsive organic semiconducting materials. For instances, Samori and co-workers reported the reversible modulation of device currents for FETs with photoresponsive semiconducting layers by blending of photochromic diarylethenes with organic semiconductors. [8a-c] Photochromic molecules were also inserted into the dielectric layer and the electrode-semiconductor interface to fabricate FETs with photoregulation functions. [10] We have just devised a new approach to photoresponsive polymeric semiconductor by incorporating azobenzene units into the side chains. [11a] Furthermore, these photoresponsive FETs were successfully utilized to fabricate memory devices for which the programming, reading and erasing signals are different without mutual interferences. [10b] It is noted that FETs with organic and polymeric semiconductors have also been investigated for nonvolatile memory It is shown that the semiconducting performance of field-effect transistors (FETs) with PDPP4T (poly(diketopyrrolopyrrolequaterthiophene)) can be reversibly tuned by UV light irradiation and thermal heating after blending with the photochromic hexaarylbiimidazole compound (p-NO 2 -HABI). A photo-/thermal-responsive FET with a blend thin film of PDPP4T and p-NO2 -HABI is successfully fabricated. The transfer characteristics are altered significantly with current enhanced up to 10 6 -fold at V G = 0 V after UV light irradiation. However, further heating results in the recovery of the transfer curve. This approach can be extended to other semiconducting polymers such as P3HT (poly(3-hexyl thiophene)), PBTTT (poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene)) and PDPPDTT (poly(diketopyrrolopyrrole-dithienothiophene)). It is hypothesized that TPIRs (2,4,5-triphenylimidazolyl radicals) formed from p-NO 2 -HABI after UV light irradiation can interact with charge defects at the gate dielectric-semiconducto...

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“…Diffusion of TPIR is thus annihilated [102]. The back-reaction is considerably accelerated and takes place in 180 ms. Other compounds, structured identically, have been the subject of several studies to modulate photochromic properties [103] or to understand the photodissociation mechanism [104].…”

Section: Fast Photochromic Systems: Reverting Back Spontaneously To Tmentioning

confidence: 99%

Introduction: Organic Photochromic Molecules

Nakatani

Piard

et al. 2016

Photochromic Materials: Preparation, Properties and Applications

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Ultrafast Photodissociation Dynamics of a Hexaarylbiimidazole Derivative with Pyrenyl Groups: Dispersive Reaction from Femtosecond to 10 ns Time Regions

Cited by 84 publications

References 44 publications

Atomic scale insights into structure instability and decomposition pathway of methylammonium lead iodide perovskite

Atomic scale insights into structure instability and decomposition pathway of methylammonium lead iodide perovskite

Photo‐/Thermal‐Responsive Field‐Effect Transistor upon Blending Polymeric Semiconductor with Hexaarylbiimidazole toward Photonically Programmable and Thermally Erasable Memory Device

Introduction: Organic Photochromic Molecules

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