Abstract
In recent years, perovskite solar cells (PSCs) have emerged as the most promising photovoltaic technology. Record devices with an efficiency above 20% have been reported. High efficiency is due to the amazing properties of the hybrid perovskite layer and, also, to the additional layers which are in contact with the absorber material. In the classical cell structures, the hybrid perovskite layer is supported on a wide bandgap layer of a n-type semiconductor oxide. This layer is very important for the optimized cell functioning since it plays multiple key roles. Firstly, as a selective contact, it permits the charge separation by receiving the photoelectrons from the perovskite absorber. The oxide conduction band energy level is then important. The interface between the oxide and the perovskite must be of high quality, with reduced defects, in order to reduce the charge recombinations at the interface. The injected electrons are transported in the oxide to the front contact. The layer acts as the electron transport layer (ETL). Therefore a good conductivity is necessary. This can be achieved by using doped materials and/or highly crystalline materials. The use of 1D structure can help the charge transport.
The oxide is the substrate of the perovskite layer upon its preparation. Various techniques have been described to prepare the hybrid perovskite. The oxide sublayer influences the sensitizer loading. It has an effect on the perovskite morphology and crystallinity. We have also observed that degradation and PbI2 formation upon preparation can be greatly influenced by the oxide sublayer.
In the present talk, we will detail and discuss various oxides and structures we have used as the selective contact for the solar cells. We will notably show that oxide layers prepared by electrochemical techniques are interesting to produce efficient devices.[1-4] The roles of the oxide on one-step and two-step deposited perovskite layer properties and on the device performances will be detailed.
References
1. J. Zhang, P. Barboux, T. Pauporté, Adv. Energy Mater., 4 (18) 1400932 (2014).
2. J. Zhang, Th. Pauporté, ChemPhysChem, 16, 2836 (2015).
3. J. Zhang, Th. Pauporté, J. Phys. Chem. C, 119, 14919 (2015).
4. J. Zhang, E. J. Juárez-Pérez, I. Mora-Seró, B. Viana, Th. Pauporté, J. Mater. Chem. A., 3, 4909 (2015).
Coffee and tea will be served 20 minutes prior to the seminar.
Anyone interested is welcome to attend.