Abstract

Multiexciton harvesting from a semiconductor quantum dot has been a new approach for improving the solar cell efficiency in quantum dot sensitized solar cells (QDSC). To date, the relationship between multiexciton dissociation in a metal-semiconductor nanohybrid system and boosting the power conversion efficiency (PCE) of QDSC has never discussed. Herein, we report a detailed spectroscopic investigation of biexciton dissociation dynamics in copper indium sulfide (CuInS2, also referred as CIS) and Au-CIS nanohybrid, utilizing both time-resolved PL and ultrafast transient absorption (TA) techniques. Ultrafast transient absorption suggests the formation of biexciton in CIS NCs which efficiently dissociates in Au-CIS nanohybrids. Maximum multiexciton dissociation (MED) efficiency is determined to be, -80% at higher laser fluency; however, it was observed to be 100% at lower laser fluency. Prior to exciton dissociation electrons are captured by Au NP in the nanohybrid from the conduction band of CIS NCs which is energetically higher than the Fermi level of Au. Here we demonstrate the proof-of concept in multielectron dissociation which may provide a new approach for improving the efficiency in QDSSCs, where we found a power conversion efficiency (PCE) of Au-CIS nanohybrids up to 2.49% as compared to similar to 1.06%, for pure CIS NCs in similar condition. This finding can be an efficient approach toward the design and development of efficient solar cell and optoelectronic devices using the principles of multiexciton generation and extracting multiexcitons in a metal-semiconductor nanohybrid system.