MAXIMUM CONTRAST FROM ELECTROCHROMIC MATERIALS: LIMITATIONS OF DUAL SYSTEMS
Javier Padilla, Venkataramanan Seshadri, Gregory A. Sotzing and Toribio F.Otero
Center for Electrochemistry and Intelligent Materials, UPCT,
Spain
Institute of Materials Science UCONN,
USA
234th ACS NATIONAL MEETING 2007, BOSTON AUGUST 19th-23th
ELECTROCHROMIC DEVICES: ELECTROCHEMICAL CELLS (WITH INTERESTING APPLICATIONS)
+- electrodes
Ionic conducting medium
e-
ions
Number of publications
related to synthesis and
electrochromism (1997-2007): 505
Number of publications
about optimization of contrast: 1 !!!!
J. Y. Lim, H. C. Ko, H. Lee, Synthetic Metals, 155 (2005) 595.
MOTIVATION
Observation
Absorbance A=-log(If/Ii)=Cd
Magnitudes
Thickness of the material
Molar absortivity of the material
Concentratión of absorbent species(directly related to oxidation-reduction)
Contrast ~ 0 Contrast ~ 0Máximum contrast?
Quantified by means of the
Absorbance= -log(If/Ii)
Transmittance T=10-A
Contrast T=Tc-Td
Ii
If
Con
tras
t
???
STARTING POINT
Lambert-Beer law
LAMBERT-BEER LAW…
A=Cd
A=q
C number of absorbent speciesnumber of absorbent species q
Absorbent species
Photon
q
Coloration efficiency
Charge per surface unit
OBTENTION OF MAXIMUM CONTRAST FOR A SINGLE POLYMER
Absorbance-redox charge relation
Electrochemical characterization
Optical characterization
A=q T = exp(-q) =2.303
T = 100[exp(-cq) - exp(-dq)]
J. Padilla, V. Seshadri, G. A. Sotzing, T. F. Otero, Electrochem. Commun. 2007, 9, 1931.
ONLY ONE FILM TO OBTAIN ALL THE INFORMATION!!!
DUAL SYSTEMS. COMPLEMENTARY POLYMERS
+ =
PBEDOT-NMCz PEDOT
Cathodic coloration
Anodic coloration
EXPECTED BENEFITS:LONGER LIFETIMEENHANCED CONTRAST
25 Combinaciones. Simulación
Experimental confirmation
Dual combinations: Theoretical prediction
Individual characterization
OBTENTION OF MAXIMUM CONTRAST FOR DUAL SYSTEMS
Absorbance of a dual system=Sum of individual abosorbances
Redox charge range 0-5 mCcm-2
1032 combinations!!!
Maximum dual contrast < Maximum individual contrast !!!!
System chosen: PEDOT/PBEDOT-NMCz
T = 100[exp-(c1q1+c2q2) - exp-(d1q1+d2q2)]
OBTENTION OF MAXIMUM CONTRAST FOR DUAL SYSTEMS
J. Padilla et al (submitted)
CONCLUSIONS
•EASY EXPERIMENTAL METHOD TO OBTAIN CONTRAST OF AN ELECTROCHROMIC MATERIAL AS A FUNCTION OF REDOX CHARGE. ONE FILM = COMPLETE INFORMATION
•APPLICATION TO DUAL SYSTEMS
•OPTICAL LIMITATION OF DUAL SYSTEMS: MAXIMUM CONTRAST OF THE DUAL SYSTEM IS LOWER THAN THAT OF ONE THE INDIVIDUAL MATERIALS ALONE
234th ACS National Meeting (August 19-23, 2007). Our overall theme is “Biotechnology for Health and Wellness” (BIOHW)
Biomimetics, Artificial Muscles & Nano-Bio 2007
Scientists Meet DoctorsCartagena, Spain, Europe, Nov 6-7-8-9, 2007
To the memory of Prof. A. MacDiarmid, he had accepted our invitation as plenary lecturer of the congress and his nomination as Honorary Doctor of the
Polytechnic Univ. of Cartagena.
Major areas of interest are:Biomimetics, Artificial Muscles (Polymeric or Artificial Muscles for the Failing Heart. (One session for medical applications)Nano-Bio
COME AND JOIN US AT THE 4th WORLD CONGRESS ON BIOMIMETIC,ARTIFICIAL MUSCLES AND
NANO-BIO
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OPTIMIZATION OF THE PRODUCTION PROCESS
Studied polymer PBEDOT-NMCz
Process rate
Energy consumption
Quality of the films
J. Padilla, T. F. Otero, Journal of Solid State Electrochemistry 2007, DOI 10.1007/s10008-007-0346-9
Concepts •Electrochromic potential window
•Electrochromic charge•Characterization of electrochromic
films by their redox charge
INDIVIDUAL SYSTEMS
Potencial V vs Ref electrode
J. Padilla, V. Seshadri, G. A. Sotzing, T. F. Otero, J. Electroanal. Chem. 2007, in press
a) Two layers of 0.069 and 0.654 absorbance (555 nm) b) Addition of a layer with 0.315 absorbance (555 nm) results in a loss of 36.97 %T in the clear layer, and only 10.72 %T in the dark layer. Loss in transmittance due to an additional absorbent layer is greater for a clear state. c) Evolution of the transmittance in the clear and dark states of PBPMOM-ProDOT films when an additional layer of PBEDOT-NMCz (3.85 mCcm-2, 0.1983 and 0.5179 absorbance in its clear and dark states, respectively) is included. d) Evolution of the corresponding contrasts (PBPMOM-ProDOT films alone or with the added PBEDOT-NMCz film).