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π‑Conjugated Indole-Based 2D Perovskite Microcavities for Self-Powered Ultraviolet Photodetection
Meenakshi Pegu1, Mukesh K Thakur2, Sudhir K Saini3
1Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163, Italy.
Chemistry of Materials : a Publication of the American Chemical Society
|August 14, 2026
Summary
We synthesized TPA2PbBr4, a novel 2D layered halide perovskite, using tryptammonium spacers for enhanced structural and electronic properties. This material shows promise for UV photodetectors and optoelectronics due to its strong excitonic features and microcavity effects.
Area of Science:
- Materials Science
- Solid-State Physics
- Optoelectronics
Background:
- Two-dimensional layered halide perovskites (2DLPs) offer tunable optoelectronic properties.
- Incorporating π-conjugated organic spacers can enhance structural rigidity and electronic coupling.
- Developing stable and efficient materials for UV optoelectronics remains a key challenge.
Purpose of the Study:
- To synthesize and characterize a novel 2DLP, TPA2PbBr4, utilizing tryptammonium (TPA) as a π-conjugated organic spacer.
- To investigate the structural, thermal, and optoelectronic properties of TPA2PbBr4.
- To evaluate the performance of TPA2PbBr4 in UV photodetector applications.
Main Methods:
- Synthesis of TPA2PbBr4 microcrystals via slow vapor diffusion.
- Structural characterization using powder and single-crystal X-ray diffraction (XRD).
- In situ temperature-dependent XRD for thermal stability analysis.
- Optical measurements including absorption, photoluminescence, and reflectance spectroscopy.
- Fabrication and characterization of planar and vertical photodetectors (PDs).
Main Results:
- TPA2PbBr4 exhibits a Ruddlesden-Popper-type structure with high thermal stability (183–433 K).
- Sharp excitonic absorption (398 nm) and photoluminescence (407 nm) peaks were observed.
- Thin films display strong optical confinement with Fabry-Pérot microcavity modes and polariton formation.
- Planar PDs show stable UV photoresponse, low dark current, responsivity of 1 mA/W, and detectivity of 2.2 × 10^10 Jones.
- Vertically configured PDs demonstrate self-powered operation due to a built-in electric field.
Conclusions:
- TPA2PbBr4 is a structurally robust 2DLP with significant excitonic features and microcavity effects.
- The material demonstrates excellent potential for UV-selective photodetectors.
- Its properties are suitable for low-power optoelectronic applications, leveraging π-conjugated organic spacer chemistry.
