A novel π–conjugated Zn⟵S→Zn unit interface in the ZnS/Zn(S)2L inorganic/orgainc hybrids for significant photoelectric response

Abstract

By using a novel Zn(S)2L complex (L=N–hexyl–3–{2–(4–(2,2′:6′,2′′–terpyridin–4′–yl)phenyl)ethenyl}carbazole) as a surface stabilizing agent, the self–assembled microspheres of Zn(S)2L–capped ZnS nanocrystals are obtained in a simple ethanol solvothermal process. Because of the strong π character of the two terminal sulfur atoms (S1– valence state) in the Zn(S)2L complex, the Zn(S)2L complex could incorporate ZnS nanocrystals together by a homologous Zn⟵S→Zn unit interface. In the work, the homologous Zn⟵S→Zn unit interface is proposed to function as a π–conjugated bridge for effective electron–transfer transition from Zn(S)2L moiety to ZnS nanocrystal to significantly improve the photoelectric response performance, such as the long lifetime of photogenerated charge carriers from 8×10−8s to 4×10−5s and the high recombination luminescence quantum efficiency (QE) up to 69%, which are confirmed by the systematically investigation with Raman spectra, XPS spectra, Uv–vis absorption spectra, photoluminescence (PL) spectra and transient photovoltage (TPV) technique. The ZnS/Zn(S)2L used as extra electron donor in organic/inorganic hybrid solar cell device could increase performance up to about 30%.