TiO 2 /Sb 2 S 3 /P3HT Based Inorganic–Organic Hybrid Heterojunction Solar Cells with Enhanced Photoelectric Conversion Performance

Hybrid inorganic–organic heterojunction solar cells (HHSCs) are successfully fabricated using Sb 2 S 3 as a light-absorbing semiconductor, TiO 2 nanorods (NRs) as an electron-transport layer, and poly-3 (hexylthiophene) (P3HT) as both a hole conductor and light absorber. The enhanced photo-to-electric conversion performance is expected to (1) enhance optical absorption in the visible light region by Sb 2 S 3 and (2) photo-generate highly efficient charge carrier separation at TiO 2 /Sb 2 S 3 and Sb 2 S 3 /P3HT heterojunction interfaces. The power conversion efficiency (PCE) of HHSCs improves approximately fourfold by inserting the Sb 2 S 3 layer, which can be further enhanced about four more times by optimizing the length of TiO 2 nanorod arrays (NRAs). Finally, the mechanism to illustrate the effect of the length of TiO 2 NRs on the PCE is discussed. This leads to a theory for achieving high-efficiency inorganic–organic solar cells.