TiO2 composite electron transport layers for planar perovskite solar cells by mixed spray pyrolysis with precursor solution incorporating TiO2 nanoparticles |
Surface morphology of TiO2 layers without (a) and with incorporation of 25 nm (b), 60 nm (c), and 100 nm (d) TiO2 nanoparticles. The scale bar is 200 nm. |