• Title, Summary, Keyword: PCBM molecules

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Ultra-Low Powered CNT Synaptic Transistor Utilizing Double PI:PCBM Dielectric Layers (더블 PI:PCBM 유전체 층 기반의 초 저전력 CNT 시냅틱 트랜지스터)

  • Kim, Yonghun;Cho, Byungjin
    • Korean Journal of Materials Research
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    • v.27 no.11
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    • pp.590-596
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    • 2017
  • We demonstrated a CNT synaptic transistor by integrating 6,6-phenyl-C61 butyric acid methyl ester(PCBM) molecules as charge storage molecules in a polyimide(PI) dielectric layer with carbon nanotubes(CNTs) for the transistor channel. Specifically, we fabricated and compared three different kinds of CNT-based synaptic transistors: a control device with $Al_2O_3/PI$, a single PCBM device with $Al_2O_3/PI:PCBM$(0.1 wt%), and a double PCBM device with $Al_2O_3/PI:PCBM$(0.1 wt%)/PI:PCBM(0.05 wt%). Statistically, essential device parameters such as Off and On currents, On/Off ratio, device yield, and long-term retention stability for the three kinds of transistor devices were extracted and compared. Notably, the double PCBM device exhibited the most excellent memory transistor behavior. Pulse response properties with postsynaptic dynamic current were also evaluated. Among all of the testing devices, double PCBM device consumed such low power for stand-by and its peak current ratio was so large that the postsynaptic current was also reliably and repeatedly generated. Postsynaptic hole currents through the CNT channel can be generated by electrons trapped in the PCBM molecules and last for a relatively short time(~ hundreds of msec). Under one certain testing configuration, the electrons trapped in the PCBM can also be preserved in a nonvolatile manner for a long-term period. Its integrated platform with extremely low stand-by power should pave a promising road toward next-generation neuromorphic systems, which would emulate the brain power of 20 W.

Theoretical and quantitative structural relationships of the electrochemical properties of Cis-unsaturated thiocrown ethers and n-type material bulk-heterojunction polymer solar cells as supramolecular complexes [X-UT-Y]@R (R = PCBM, p-EHO-PCBM, and p-EHO-PCBA)

  • Taherpour, Avat Arman;Biuki, Farzaneh
    • Journal of Information Display
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    • v.12 no.3
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    • pp.145-152
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    • 2011
  • Since the discovery of fullerenes as a class of nanostructure compounds, many potential applications have been suggested for their unusual structures and properties. The isolated pentagon rule (IPR) states that all pentagonal carbon rings are isolated in the most stable fullerene. Fullerenes $C_n$ are a class of spherical carbon allotrope group with unique properties. Electron transfer between fullerenes and other molecules is thought to involve the transfer of electrons between the molecules surrounding the fullerene cage. One class of electron transfer molecules is the methanofullerene derivatives ([6,6]-phenyl $C_{61}$-butyric acid methyl ester (PCBM), 4-(2-ethylhexyloxy)-[6,6]-phenyl $C_{61}$-butyric acid methyl ester (p-EHO-PCBM), and 4-(2-ethylhexyloxy)-[6,6]-phenyl $C_{61}$-butyric acid (p-EHO-PCBA), 10-12). It has been determined that $C_{60}$ does not obey IPR. Supramolecular complexes 1-9 and 10-12 are shown to possess a previously unreported host.guest interaction for electron transfer processes. The unsaturated, cis-geometry, thiocrown ethers, (1-9) (described as [X-UT-Y], where X and Y indicate the numbers of carbon and sulfur atoms, respectively), are a group of crown ethers that display interesting physiochemical properties in the light of their conformational restriction compared with a corresponding saturated system, as well as the sizes of their cavities. Topological indices have been successfully used to construct mathematical methods that relate structural data to various chemical and physical properties. To establish a good relationship between the structures of 1-9 with 10-12, a new index is introduced, ${\mu}_{cs}$. This index is the ratio of the sum of the number of carbon atoms ($n_c$) and the number of sulfur atoms ($n_s$) to the product of these two numbers for 1-9. In this study, the relationships between this index and oxidation potential ($^{ox}E_1$) of 1-9, as well as the first to third free energies of electron transfer (${\Delta}G_{et(n)}$, for n = 1-3, which is given by the Rehm-Weller equation) between 1-9 and PCBM, p-EHO-PCBM, and p-EHO-PCBA (10-12) as [X-UT-Y]@R(where R is the adduct PCBM, p-EHO-PCBM, and p-EHO-PCBA group) (13-15) supramolecular complexes are presented and investigated.

Interface modification of CH3NH3PbI3/PCBM by pre-heat treatment for efficiency enhancement of perovskite solar cells

  • Sutthana, Sutthipoj;Hongsith, Kritsada;Ruankham, Pipat;Wongratanaphisan, Duangmanee;Gardchareon, Atcharawon;Phadungdhitidhada, Surachet;Boonyawan, Dheerawan;Kumnorkaew, Pisist;Tuantranont, Adisorn;Choopun, Supab
    • Current Applied Physics
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    • v.17 no.4
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    • pp.488-494
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    • 2017
  • An interfacial modification of $CH_3NH_3PbI_3/PCBM$ is investigated by pre-heating PCBM solution before spin-coating on the $CH_3NH_3PbI_3$layer.By adjusting PCBM concentration, PCBM films were optimized to form homogeneous films. Besides, the pre-heat treatment of PCBM solution exhibits a better covered area over $CH_3NH_3PbI_3$ layer with reduced pinhole compared with the non-heat treatment. This can be explained by the higher thermal energy PCBM molecules of the pre-heat solution leading to higher molecule mobility that can reorganizes a structural as well as enhance the diffusion and enhance coverage of PCBM films over $CH_3NH_3PbI_3$. The optimized cell is enhanced with average power conversion efficiency from 4.59% up to 5.76% (6.44% maximum) by heat treatment. To investigate interface between $CH_3NH_3PbI_3$ and PCBM, the contact angle was measured and found that the contact angle of PCBM films were higher after heat treatment suggesting re-alignment and better orientation of PCBM on perovskite film. The better orientation of PCBM can be explained in term of hydrophilic/hydrophobic property of the interface between $CH_3NH_3PbI_3$ and PCBM. These results suggest that pre-heat treatment of PCBM solution has ability to modify the interface for better orientation of PCBM and resulting in efficiency enhancement due to better carrier transport direction at the $CH_3NH_3PbI_3/PCBM$ interfaces for perovskite solar cells. In addition, the better orientation that the head (non-polar)is oriented at outer surface can also prevent the solar cells from surrounding moisture.