Investigation of PbS nanocrystals sensitized extremely thin absorber (ETA) solar cell

Colloidal PbS nanocrystals (NCs) were prepared by an environmental friendly route. The as-prepared colloidal PbS nanocrystals were characterized by powdered X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM). The ground state excitonic transition energies determined from the position of the first excitonic absorption peaks (2.5 nm±0.2 (J1), 2.8 nm±0.15 (J2) and 3.1 nm±0.3 (J3) were 1.71, 1.35 and 1.15 eV respectively). These PbS nanocrystals were then used to sensitize a nanostructured ZnO-SnO2 electrode by using In2S3 as a buffer layer. The results showed that sensitization procedure of PbS NCs with electrode played a significant role in the charge separation and transport. The cell fabricated by PbS NCs in which linker molecules were exchanged on the surface of electrode showed considerably higher incident to photon conversion efficiency (IPCE) compared to pre-ligand modified PbS NCs. The findings presented here can potentially be applied for the design of low-cost ETA devices for commercial applications.