Abdelhak Belaidi

Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces

With a power conversion efficiency (PCE) exceeding 22 %, perovskite solar cells (PSCs) have thrilled photovoltaic research. However, the interface behavior is still not understood and is a hot topic of research: different processes occur over a hierarchy of timescales, from femtoseconds to seconds, which makes perovskite interface physics intriguing. Herein, through femtosecond transient absorption spectroscopy with spectral coverage extending into the crucial IR region, the ultrafast interface-specific processes at standard and newly molecularly engineered perovskite interfaces in state-of-the-art PSCs are interrogated. Ultrafast interfacial charge injection occurs with a time constant of 100 fs, resulting in hot transfer from energetic charges and setting the timescale for the first step involved in the complex charge-transfer process. This is also true for 20 % efficient devices measured under real operation, for which the femtosecond injection is followed by a slower picosecond component. These findings provide compelling evidence for the femtosecond interfacial charge-injection step and demonstrate a robust method for the straightforward identification of interfacial non-equilibrium processes on the ultrafast timescale.

Preparation of Cu2O and Cu2O@Cu Core-Shell Nanostructures by a Simple Chemical Technique

R. Al-Gaashani, Md. Anower Hossain, Fahhad H. Alharbi, Abdelbaki Benamor, Abdelhak Belaidi, Belabbes Merzougui, N. Tabet Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation Doha, Qatar ralgaashani@qf.org.qa; ntabet@hbku.edu.qa Physics Department, Faculty of Education, Thamar University Dhamar, Republic of Yemen rashad_jashani@yahoo.com Gas Processing Center, Qatar University PO Box 2713, Doha, Qatar benamor.abdelbaki@qu.edu.qa