Regensburg 2016 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 80: Hybrid and Perovskite Photovoltaics IV (Joint session of CPP, DF, DS and HL, organized by HL)

HL 80.13: Talk

Thursday, March 10, 2016, 18:15–18:30, H2

Luminescence blue-shift with decreasing size of perovskite needles. — •Amala Elizabeth and Katrin F.Domke — Molecular Spectroscopy Department,Max Planck Institute for Polymer Research, Mainz, 55128, Germany

Despite revolutionizing the photovoltaic industry by helping create highly efficient thin film solar cells, many intrinsic properties of organometallic halide perovskites still remain unknown. A complete understanding of the interplay of size, structure and electronic nature in determining the optical properties of thin film perovskites is crucial to fully exploit them for solar cell applications.

We studied methylammonium lead iodide perovskite thin films of ordered needles of varying submicron size. Energy-dispersive X-ray and IR spectroscopies reveal that the needles are chemically identical. While crystallinity is preserved in all samples, XRD and Raman spectra show a relative increase in the crystalline lead iodide content with decreasing needle size. Interestingly, we observe a blue-shift of  40 meV in both luminescence peak position and UV-vis absorption onset with decreasing needle size. Here, we discuss possible origins of the unexpected band gap increase with decreasing perovskite needle size, such as methyl ammonium cation orientational ordering [1] and lead iodide content [2].

References:

1. C. Quarti et al., J.Phys.Chem Lett. 5 (2014), 279-284.

2. Q.Shen et al., Nano Lett. 14 (2014), 4158-4163.