Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
Publication date: 20th April 2022
Lead-halide perovskite solar cells (PSCs) are currently the most promising emergent thin-film photovoltaic technology [1], having already reached power conversion efficiency (PCE) levels of state-of the-art wafer-based silicon cells [2]. The class of wide bandgap PSCs has also demonstrated high PCE values, thus becoming highly attractive for top sub-cells in tandem devices constructed with silicon or other types of bottom sub-cells [3,4]. In this study [5], wide bandgap double-halide (Cs0.17FA0.83PbI(3-x)Brx) perovskite absorbers were developed with different bromine content, aiming to obtain bandgap values from 1.66 to 1.74 eV, by a glovebox-free (ambient) procedure. The perovskite absorber layers were characterized by optical methods. The lattice constants of the well-crystallized perovskite layers were determined by XRD measurements. The surface imaging and morphological analyses were performed by SEM and AFM techniques respectively.
For the mesoscopic perovskite solar cell fabrication, low-cost inorganic materials, i.e. TiO2 and CuSCN, were used for the electron and hole transport layers, respectively. Initial PCE values between 11.1% and 15.1% were obtained for the WBG-PSCs. However, after optimizing the processing steps of the devices with 1.70 eV bandgap perovskite absorber, PSCs with high reproducibility and stability (80% initial PCE after 3500 hours) properties and remarkable PCEs up to 16.4% were attained with ambient and high-humidity (70%) fabrication conditions [5].
The aforementioned optimization steps include a humidity-insensitive antisolvent method [6], in which it was found crucial to preheat the substrate before the perovskite deposition, as well as to preheat the antisolvent and apply the antisolvent washing from a very close tip-sample distance, which enhances the evaporation and crystallization process of the perovskite film by reducing the moisture effects.
The work received funding from the European Union’s Horizon 2020 research and innovation programme under the project ENLIGHTEN (H2020-MSCA-IF-2019, Grant No. 891686) and Synergy (H2020-Widespread-2020-5, CSA) grant agreement No. 952169. The work was also financed by national funds from FCT, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N, and of the project LocalEnergy (PTDC/EAM-PEC/29905/2017).