Keywordsphotovoltaic; upconversion; efficiency; solid-state dye-sensitized solar cells; TiO2; nitrogen doping; photo-physics; photo-response; spiro-OMeTAD; carbon nanotubes; solar cells; carbon nanotube (CNT)/Si heterojunction solar cells; double-walled carbon nanotube (DWCNT); multi-walled carbon nanotubes (MWCNT); solar cells; nanostructures; light trapping; small molecule; organic solar cell; bulk-heterojunction; optical simulation; small molecule; fluorinated phenyl (DFP) groups; organic solar cell; solution process; nanoscale phase separation; ultraviolet plasmonics; aluminium nanoparticles; light incoupling; light trapping; solar cells; GaInP/GaInAs/Ge triple-junction solar cells; Ag ellipsoidal nanoparticles; thermal treatment parameters; current-match; quantum dot-sensitized solar cells; photocurrent; alloy; PbS; bulk heterojunction solar cells; hybrid solar cells; nanocrystals; quantum dots; conjugated polymers; post-synthetic treatment; thermal annealing; long-term stability; open-ended freestanding TiO2 nanotube arrays; dye-sensitized solar cells; plasmonic; scattering; anodization; photovolatics; solar cells; nanostructures; nanomaterials; quantum dots; graphene; carbon; photovoltaics; solar cells; nano-photonics; solar cell; light-trapping; scattering