Baran Group Meeting

Terry Lou Materials development (Cont'd) Photosensitizer (Dye) - Strong absorption at visible region and near-IR - Dye-Sensitized Solar Cells Anchoring group to strongly bind onto semiconductor surface (-COOH, -H2PO 3, -SO 3 H, etc.) Excited state energy E(S*) > Ec TBAOOC COOH .COOH HOOC COOTBA 8=0= COOH -N=G=S Baran Group Meeting Jun 5, 2021 HOOC 8=0=4= COOH N719 n = 10.2%; enhanced Voc; reference dye for studies COOH N749 (Black dye) n = 10.4%; IPCE spectrum extended to 920 nm N886 n = 5.9%; IPCE spectrum up to 900 nm, max = 40% Redox potential of oxidized dye more +ve than electrolyte Avoid aggregation (unable to inject e- to semiconductor) by structure optimization or addition of coadsorbers (e.g. 4-tert-butylpyridine (TBP), deoxycholic acids, acetic acid) High turnover number (photostable, electrochemically and thermally stable). HOOC COOH HOOC соон COONa H13 R R R R R 0 0. M M M M unidentate bidendate chelating bidentate bridging H-bonded H-bonded Ru complexes HOOC HOOC COOH 72+ HOOC HOOC COOH (Desilvestro, 1985) First reported DSSC IPCE 44% (460 nm) COOH 2Cr HOOC HOOC HOOC (O'Regan, 1991) n = 7.1%; IPCE 97% (520 nm) HOOC COOH Z907 S=C=N* -Z== CHie n = 7%; improved stability .COOH HOOC 8=0=N- N3 (Grätzel, 1993) OOH HOOC n = 10%; IPCE spectrum up to 800 nm COOH COOH (Bessho, 2009) n = 10.1%; replaced -NCS Z910 -2=0=0 n = 10.2%; excellent thermal stability Summary: HOOC C101 Cg H₁3 n = 11%; retain >90% performance after 1,000 h (1 sun, 60 °C) - MLCT (d→л*) upon photo-excitation Dicarboxylate-bpy provides good anchoring electronic coupling of the dye* with TiO2 CB Second bpy can be modified with EDW to broaden the absorption spectra and to increase the molar extinction coefficient -NCS as EDG to raise the HOMO energy of the complex, leading to a red-shifted absorption, but is the weakest part of Ru complex 4

View entire presentation