Synergistic surface modification of tin-lead perovskite solar cells
Advanced Materials Wiley 35:9 (2023) 2208320
Abstract:
Interfaces in thin-film photovoltaics play a pivotal role in determining device efficiency and longevity. Herein, we study the top surface treatment of mixed tin-lead (∼1.26 eV) halide perovskite films for p-i-n solar cells. We are able to promote charge extraction by treating the perovskite surface with piperazine. This compound reacts with the organic cations at the perovskite surface, modifying the surface structure and tuning the interfacial energy level alignment. In addition, the combined treatment with C<sub>60</sub> pyrrolidine tris-acid (CPTA) reduces hysteresis and leads to efficiencies up to 22.7%, with open-circuit voltage values reaching 0.90 V, ∼92% of the radiative limit for the band gap of this material. The modified cells also show superior stability, with unencapsulated cells retaining 96% of their initial efficiency after >2000 hours of storage in N<sub>2</sub> and encapsulated cells retaining 90% efficiency after >450 hours of storage in air. Intriguingly, CPTA preferentially binds to Sn<sup>2+</sup> sites at film surface over Pb<sup>2+</sup> due to the energetically favoured exposure of the former, according to first-principles calculations. This work provides new insights into the surface chemistry of perovskite films in terms of their structural, electronic, and defect characteristics and we use this knowledge to fabricate state-of-the-art solar cells.Composition–Property Mapping in Bromide-Containing Tin Perovskite Using High-Purity Starting Materials
ACS Applied Energy Materials American Chemical Society (ACS) 5:12 (2022) 14789-14798
Challenges and strategies toward long-term stability of lead-free tin-based perovskite solar cells
Communications Materials Springer Nature 3:1 (2022) 104
A Universal Surface Treatment for p-i-n Perovskite Solar Cells.
ACS applied materials & interfaces 14:50 (2022) 56290-56297
Abstract:
Perovskite interfaces critically influence the final performance of the photovoltaic devices. Optimizing them by reducing the defect densities or improving the contact with the charge transporting material is key to further enhance the efficiency and stability of perovskite solar cells. Inverted (p-i-n) devices can particularly benefit here, as evident from various successful attempts. However, every reported strategy is adapted to specific cell structures and compositions, affecting their robustness and applicability by other researchers. In this work, we present the universality of perovskite top surface post-treatment with ethylenediammonium diiodide (EDAI2) for p-i-n devices. To prove it, we compare devices bearing perovskite films of different composition, i.e., Sn-, Pb-, and mixed Sn-Pb-based devices, achieving efficiencies of up to 11.4, 22.0, and 22.9%, respectively. A careful optimization of the EDAI2 thickness indicates a different tolerance for Pb- and Sn-based devices. The main benefit of this treatment is evident in the open-circuit voltage, with enhancements of up to 200 mV for some compositions. In addition, we prove that this treatment can be successfully applied by both wet (spin-coating) and dry (thermal evaporation) methods, regardless of the composition. The versatility of this treatment makes it highly appealing for industrial application, as it can be easily adapted to specific processing requirements. We present a detailed experimental protocol, aiming to provide the community with an easy, universal perovskite post-treatment method for reliably improving the device efficiency, highlighting the potential of interfaces for the field.Perovskite/Perovskite Tandem Solar Cells in the Substrate Configuration with Potential for Bifacial Operation.
ACS materials letters 4:12 (2022) 2638-2644