The present work reports on the development of a class of thin-film transparent electrodes for the PV devices based on spray coating of carboxyl functional multi-walled carbon nanotubes (MWCNT-COOH) aqueous dispersion and thin-film transparent transistors based on ink-jet printing MWCNT-COOH inks with proper fluidic characteristics. The MWCNT-COOH inks were formulated by addition of PEDOT-PSS to MWCNT-COOH aqueous dispersion. SEM shows the spray coating MWCNT-COOH films and the ink-jet printing MWCNT-COOH films are uniform. UV-vis transmission spectra indicate high transparency. Four probe measurements show excellent sheet resistance. The present work demonstrates that spray coating MWCNT-COOH films are promising for transparent electrodes in flexible and large area PV electronics and that ink-jet printed MWCNT-COOH films in patterns are promising for transparent transistors.