| AVS 62nd International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS+SS-WeA |
| Session: | Characterization of Buried Interfaces |
| Presenter: | Jean-Jacques Pireaux, University of Namur, Belgium |
| Authors: | Y. Busby, University of Namur, B-5000 Namur, Belgium F. Matteocci, University of Rome “Tor Vergata”, Italy G. Divitini, University of Cambridge, UK S. Cacovich, University of Cambridge, UK C. Ducati, University of Cambridge A. di Carlo, University of Rome “Tor Vergata”, Italy J.-J. Pireaux, University of Namur, Belgium |
| Correspondent: | Click to Email |
Hybrid halide perovskite solar cells (PSCs) have received much attention during the very last years because of their very promising cost/performance ratio. Different architectures and preparation methods have been tested, but still some general guidelines for their optimization are missing. In particular, the interfaces are now well known to play a dominant role in the device performances but have been so far poorly studied.
In this work, we correlated the solar cell characteristics to their interface composition and morphology in PSCs deposited by different procedures (single-step, double-step by dipping, double-step by a vacuum assisted technique) and different conversion environments (air, vacuum and nitrogen atmosphere). The interface quality is found to be affected by the perovskite conversion method and in particular from the environment where the conversion is performed. Power conversion efficiencies between 7 and 14.5% have been measured from the characteristics of the differently prepared cells. The morphology, crystal size and interdiffusion have been fully characterized by scanning transmission electron microscopy (STEM), equipped with high resolution energy-dispersive X-ray spectroscopy (EDX). Interfaces have been further characterized by depth profile techniques by combining ion beam sputtering with atomic and molecular composition analysis with X-Ray photoelectron spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). In particular these techniques allowed detecting and evaluating the diffusion of metals into the hole transport material (SpiroOMetAD) and iodine and chlorine diffusion in the TiO2 back contact. Interestingly, the higher oxygen content perovskite formed in air is not associated to a sensibly lower (short term) efficiency of the solar cell.