Control of Crystal Structures and Optical Properties with Hybrid Formamidinium and 2-Hydroxyethylammonium Cations for Mesoscopic Carbon-Electrode Tin-Based Perovskite Solar Cells

Abstract

Alcohol-based bifunctional ammonium cations, 2-hydroxyethylammonium (HEA+), HO­(CH2)2NH3 +, were introduced into formamidinium (FA+) tin-based perovskites (HEA x FA1–x SnI3; x = 0–1) to absorb light in carbon-based mesoscopic solar cells. We found that HEA+ cations play a key role to control the crystal structures, the lattice structures altered from orthorhombic (x = 0) to rhombohedral (x = 0.2–0.4) with greater symmetry. When x was increased to 0.6–1.0, tin and iodide vacancies were formed to generate 3D-vacant perovskites (HEA x FA1–x Sn0.67I2.33, x ≥ 0.6) with a tetragonal structure. Tin-based perovskites in this series were fabricated into mesoporous solar cells using one-step drop-cast (DC), two-step solvent-extraction (SE), and SE + 3% ethylenediammonium diiodide (EDAI2) as an additive. After optimization of device performance with the SE + 3% EDAI2 approach, the HEA0.4FA0.6SnI3 (HEAI = 40%) device gave the best photovoltaic performance with J SC = 18.52 mA cm–2, V OC = 371 mV, FF = 0.562, and overall efficiency η = 3.9% after the device was stored for a period of 340 h.

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Tin Halide Perovskites: Progress and Challenges

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Potential Substitutes for Replacement of Lead in Perovskite Solar Cells: A Review

“…The light absorbers in this series are synthesized by employing mesoporous solar cells using one‐step drop‐cast (DC), two‐step solvent–solvent extraction (SE), and a solvent extraction by using ethylenediammonium diiodide (EDAI 2 ) as an additive. The fabricated solar device HEA 0.4 FA 0.6 SnI 3 displayed the photovoltaic parameters with V OC of 0.371 V, J SC of 18.52 mA cm −2 , FF of 0.562, and a stable SPCE of 3.9% for a period of 340 h . The FASnI 3 perovskite light absorbers incorporated with a diammonium cation such as propylenediammonium (PW) and trimethylenediammonium (TN) display better efficiency than the pristine FASnI 3 solar cell.…”