Grey Christoforo PhD

Abstract:

A large number of flexible polymer solar modules comprising 16 serially connected individual cells was prepared at the experimental workshop at Risø DTU. The photoactive layer was prepared from several varieties of P3HT (Merck, Plextronics, BASF and Risø DTU) and two varieties of ZnO (nanoparticulate, thin film) were employed as electron transport layers. The devices were all tested at Risø DTU and the functional devices were subjected to an inter-laboratory study involving the performance and the stability of modules over time in the dark, under light soaking and outdoor conditions. 24 laboratories from 10 countries and across four different continents were involved in the studies. The reported results allowed for analysis of the variability between different groups in performing lifetime studies as well as performing a comparison of different testing procedures. These studies constitute the first steps toward establishing standard procedures for an OPV lifetime characterization. © 2011 Elsevier B.V. All rights reserved.

Abstract:

Vacuum-based deposition is a scalable, solvent-free industrial method ideal for uniform coatings on complex substrates. However, all vacuum-deposited perovskite solar cells fabricated by thermal evaporation trail solution-processed counterparts in efficiency and stability due to film quality challenges, necessitating advancement and improved understanding. Here, we report a co-evaporation route for 1.67-eV wide-bandgap perovskites by introducing a PbCl2 co-source to optimize film quality. We promote perovskite formation with pronounced (100) “face-up” orientation and deliver a certified all vacuum-deposited solar cell with 18.35% efficiency (19.3% in the lab) for 0.25-cm2 devices (18.5% for 1-cm2 cells). These cells retain 80% of peak efficiency after 1,080 hours under the ISOS-L-2 protocol. Leveraging operando hyperspectral imaging, we provide spatiotemporal spectral insight into halide segregation and trap-mediated recombination, correlating microscopic luminescence features with macroscopic device performance while distinguishing radiative from non-ideal recombination channels. We further demonstrate 27.2%-efficient 1-cm2 evaporated perovskite-on-silicon tandems and outdoor stability of all vacuum-deposited tandems in Italy, retaining ~80% initial performance after 8 months.