Hot Hole Transfer Dynamics from CsPbBr3 Perovskite Nanocrystals

• Published in: ACS energy letters Vol. 5; no. 7; pp. 2246 - 2252
• Main Authors: De, Apurba, Das, Somnath, Samanta, Anunay
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.07.2020
• ISSN: 2380-8195; 2380-8195
• DOI: 10.1021/acsenergylett.0c01063

Transfer of the hot charge carriers prior to their cooling to the band-edge states can enhance the efficiency of a semiconductor-based solar cell much beyond its Shockley–Queisser (SQ) limiting value. Herein, we explore transfer of hot holes from the APbBr3 nanocrystals (NCs) employing a carefully chosen molecular system, 4-mercaptophenol. Ultrafast pump–probe and fluorescence measurements indeed confirm this transfer process, whose efficiency depends on the energy content of the hole, and a maximum efficiency of ∼43% is achieved with CsPbBr3 NCs for a photoexcitation energy of ∼1.46E g (E g is the band gap of the NCs). While the estimated hot hole cooling and transfer rates are quite comparable, hole transfer from the band edge is found to be a significantly slower process. The findings of the present study suggest that exceeding the SQ efficiency of the solar cells based on the perovskites can indeed be a reality.