Leader: Zelenyak Tatyana Yuryevna

Work E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. 

Scientific problem:

Halide perovskite thin-film structures with the formula ABX₃ (where A = MA⁺, FA⁺, Cs⁺; B = Pb²⁺, Sn²⁺; X = I⁻, Br⁻, Cl⁻) have attracted significant attention due to their unique optoelectronic properties, including high light absorption efficiency, tunable bandgap, high quantum efficiency, and low synthesis cost. These materials are promising for next-generation photovoltaic devices. To date, the hybrid perovskite CH₃NH₃PbI₃ has been well studied, demonstrating a high power conversion efficiency of ~25%. At the same time, inorganic perovskite CsPbI₃ is synthesized, which exhibits excellent thermal stability and an optimal bandgap (~1.7 eV), making it suitable for creating tandem solar cells. However, both materials face stability issues. The CH₃NH₃PbI₃ perovskite is vulnerable to moisture and suffers from thermal instability. In contrast, CsPbI₃ faces a different problem: a phase transition at room temperature, whereby the photoactive α-phase transforms into the non-perovskite δ-phase. Thus, CH₃NH₃PbI₃ and CsPbI₃ exhibit fundamentally different degradation mechanisms. To understand and quantitatively assess these degradation processes, a precise analysis of the elemental composition and depth distribution of elements within the material is required. Ion beam analysis methods, in particular Rutherford Backscattering Spectrometry (RBS), represent a powerful tool for addressing this challenge.

Objective: 

Aim of the work: to conduct a comparative analysis of the stability of hybrid (CH₃NH₃PbI₃) and inorganic (CsPbI₃) perovskites using ion beam analysis (RBS) methods to identify differences in degradation mechanisms, elemental migration, and structural changes induced by external factors.

Tasks:

1. Review of the literature on the CH₃NH₃PbI₃ and CsPbI₃ perovskite materials.
2. Review of the physical principles underlying the RBS method.
3. Comparative analysis of the stability of CH₃NH₃PbI₃ and CsPbI₃ perovskite thin-film structures based on RBS data and complementary methods (XRD, DSC, TGA).
4. Investigation of ion migration in both types of perovskites using RBS. Study of depth profiling for the quantitative assessment of ion diffusion (I⁻, Pb²⁺, Cs⁺, CH₃NH₃⁺) and interdiffusion at interfaces.
5. Comparative analysis of the obtained results to identify general patterns and fundamental differences in the degradation mechanisms of CH₃NH₃PbI₃ and CsPbI₃, as well as an assessment of the applicability of RBS as a tool for predicting the long-term stability of perovskite devices.

Research facilities: 

EG-5 accelerator, X-ray diffractometer, electron microscope, optical microscope, chemical synthesis laboratory, other infrastructure of the EG-5 accelerator complex and FLNP, DSC, TGA.

Minimum requirements for applicants

Solid educational background (physics, chemistry, mathematics, nanotechnology, electronics); problem-solving and practical hands-on skills; creativity; ability to work both independently and collaboratively in a multidisciplinary team; diligence and a high degree of responsibility.