Deep-red emitting zinc and aluminium co-doped copper indium sulfide quantum dots for luminescent solar concentrators

Pure CuInS₂ quantum dots (CIS QDs) exhibited poor photoluminescent (PL) performance due to more dangling bonds on their surface and thus needed a shell to form core@shell structured QDs. However, conventional shells had a higher band gap than CIS QDs so that the core@shell structured QDs showed a blue-shifted PL peak below 700 nm and narrower light absorption range. Herein, Zn and Al co-doped CIS QDs were synthesized by a facile cation exchanged method which can significantly improve the PL property emitting at ∼740 nm compared to pure CIS QDs. The enhancement of the PL property was probably attributed to Zn_Cu and Al_Cu defects in the CIS QDs which could cause electron-hole radiative recombination via defect levels, reduce the number of dangling bonds and thus minimize the nonradiative recombination through surface electron trapping. Furthermore, the PL intensity was controlled by doping time and reached the maximum at 30 min. The obtained deep-red emitting CIS QDs were employed to fabricate semi-transparent luminescent solar concentrators (LSCs) which exhibited an excellent optical efficiency of 6.97%. The success in using such Zn and Al co-doped CIS QDs could pave the way to realize high efficiency and environment-friendly LSCs for building integrated photovoltaics.