Spin-polarized lasing in quasi-2D perovskites below 200 K

Researchers reported in Science Advances spin-polarized lasing in quasi-two-dimensional (quasi-2D) perovskites, achieved by suppressing fast spin relaxation through regulation of triplet excitons. According to the authors, lasing was realized below 200 K, and its threshold was 30.2% lower than for linearly polarized excitation doi.org. The materials use the organic cations phenylethylammonium (PEA) and 1-naphthylmethylamine (NMA).

Spin-polarized lasers are considered for integrated photonic devices for secure communication, optical interconnections and other optical devices. Quasi-2D perovskites are candidates because their potential structural inversion asymmetry should give strong spin-orbit coupling (SOC), which facilitates spin injection and spin splitting of electronic bands doi.org.

Spin relaxation mechanism

Strong SOC involves a trade-off between spin injection and spin lifetimes. This makes it difficult to sustain spin polarization in the lasing regime while keeping optical gain. The authors identified the Bir-Aronov-Pikus (BAP) mechanism as the dominant spin relaxation channel that prevents spin-polarized lasing in quasi-2D perovskites doi.org.

Triplet excitons and the result

The authors modulated the reverse intersystem crossing of triplet excitons. As a result, the D'yakonov-Perel' (DP) mechanism began to play the key role, and a new, longer spin lifetime of 35.4 ps appeared at 77 K. This is about five times the lifetime induced by the BAP mechanism doi.org.

In their conclusion, the authors state that the work underscores the potential of PEA-based quasi-2D perovskites for spin-polarized lasing and contributes to progress in perovskite spintronic devices doi.org.

Quasi-2D perovskite spin-polarized lasing below 200 K achieved with 35.4 ps spin lifetime

Spin relaxation mechanism

Triplet excitons and the result

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