Master Thesis: Development of innovative solar cells based on all-organic metal-free halide perovskites

Motivation and Topic

Lead halide perovskites constitute a rising star of modern photovoltaics showing tremendous progress in solar cell efficiency rising from a few percent to more than 25% in mere 5-6 years. The fast progress in lead perovskite photovoltaics caused concerns about the toxic nature of lead stimulating research of alternative perovskite materials, for example, lead-depleted or totally lead-free metal halide perovskites. As an ultimate development of this trend, all-organic metal-free halide perovskites have been reported recently, with a general formula A(NH₄)X₃, where X = Cl, Br, and I, while A is an organic bication. Many A compounds show acceptable tolerance factors allowing the perovskite structure to form, including derivatives of piperazine, diazabicyclooctane, tetraazaadamantane, etc. However, most of such perovskites reveal bandgaps (E_g) larger than 3 eV inappropriate for solar photovoltaic applications.

Master Thesis: Development of innovative solar cells based on all-organic metal-free halide perovskites

Recently, theoretical calculations predicted a new class of narrow-bandgap metal-free perovskites, in particular, 6-ammonio-1-methyl-5-nitropyrimidin-1-ium-(NH₄)I₃, E_g = 1.74 eV, however, the feasibility of using such perovskite for solar cells is still to be evaluated. The present proposal meets this challenge and aims to test these compounds and similar nitropyrimidinium derivatives as absorbers for thin-film solar cells. This highly explorative research in all-organic perovskites with a virtually unlimited variety of possible A components is expected to yield highly innovative solar absorbers and realize unconventional cell designs, such as flexible, printable, and wearable solar cells.

Tasks

Selection and pilot synthesis of a series of substituted nitropyrimidinium bications as A-site components of A(NH₄)I₃ perovskites and the synthesis of final perovskites (alternative: synthesis of the perovskites from commercially available compounds);
spectral and structural characterization of A bication precursors and final metal-free perovskites;
preparation and characterization of pilot solar cells based on metal-free perovskite absorbers;
testing of the feasibility of upscaling the synthetic protocol to the level of high-throughput automated synthesis using robotic setups for a broader screening of possible perovskite compositions.

Approaches and methods

Methods of organic synthesis and characterization;
structural and spectral characterization by NMR, FTIR, Raman, and UV-Vis spectroscopies;
methods of photovoltaic experiments (registration of I-V dependences under AM1.5 illumination, stability tests, etc.).

Qualifications

students in Material Science, Energy Technology, Renewable Energy, and Nanotechnology;
good chemical knowledge and basic skills in spectral and structural characterization of materials.