As I mentioned here I’m posting some old ideas which I don’t expect to follow up on myself.
Here is the transcribed text (picture to come soon)
Hole Transport/Injection Layer, replacements for PEDOT/PSS
X = S, Se
Y = S, Se
R = H, F, Other?
Z = -CO2H, -SO3H, -PO3H2, -SH
Polymerized with FeCl3
1. Negative Charge balances oxidation on main chain
2. Main chain oxidation
3. S → F interaction makes chain rigid, increases conductivity
4. Hydrogen bonding to other chains or interactions with surface
Each choice for X, Y, Z and R will change work function, conductivity, transparency in oxidized state and chain shape. Also inter-chain interactions and polymer/surface interactions. Must explore entire space + maybe different choices for different situations.
Z choice important for polymer/surface interaction. For example -CO2H will have a strong interaction w/TiO2 and ZnO as well as many other oxides. -PO3H2 also works w/metal oxides + is particularly good for ITO (Neil Armstrong’s work). -SH will be good for metal surfaces, especially Au + Ag. -SO3H may have best stability.
Some versions may be water soluble when polymerized, but many may not. Can polymerize in place + wash away reduced Fe species, and unpolymerized monomer. Polymerization may or may not require heat. Can be done in water, MeOH, EtOH, IPA most likely and rinsed with same if needed.
=> Copolymers may also be advantageous
R = -(CH2CH2O)xMe or H
Add just enough acidic monomer to charge balance backbone oxidation, so polymer is not acidic overall but ethylene oxide side chains maintain solubility in water or alcohols. PEO side chains can have different end groups to change interactions with surfaces.
I. Backbone + charge delocalized along chain
II. Tri(ethylene oxide) side chain keeps polymer water soluble
III. OH endgroup increases close contact with metal oxides, useful in cases such as a tie layer TiO2-based Dye Sensitized solar cells
IV. Covalently linked anion for charge balance
V. F → S interaction holds backbone rigid, increases conductivity along chain
VI. Se → Se interactions between chains increases conductivity
VII. Ratio of monomers balances charges without excess acidic groups
(this would be for spin coating on ITO)
I. Excess PO3H2 groups have passivating effect on ITO as per work of Neil Armstrong at Arizona
II. Some phosphonate groups deprotonated to balance delocalized backbone charge
III. Positive charge delocalized along backbone
IV. Presence of S vs. Se in each position influences conductivity + work function determined by DFT calc. + experiment
V. Absence of F makes polymer more flexible = more soluble + better able to maximize surface interaction, decrease conductivity, changes work function.
R = H, F or sub Se for S
1. interchain interactions and move energy levels