Acs 2007 J.Padilla

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

THANKS FOR YOUR KIND ATTENTION

ONE LAST THING……

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

http://www.upct.es/~nano-bio/index.htm

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).