Stabilizing lead halide perovskites with quaternary ammonium cations: the case of tetramethylammonium lead iodide

N(CH3)4PbI3 is much more stable than CH3NH3PbI3, both kinetically and thermodynamically, and much less prone to water-induced degradation; the use of quaternary ammonium cations may be effective to produce more stable lead halide perovskites.

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Microfluidic Approach for Lead Halide Perovskite Flexible Phototransistors

Electronics ◽

10.3390/electronics9111852 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1852

Author(s):

Fatemeh Khorramshahi ◽

Arash Takshi

Keyword(s):

Room Temperature ◽

Lead Iodide ◽

Current Modulation ◽

Facile Fabrication ◽

Halide Perovskites ◽

P Type ◽

Methylammonium Lead Iodide ◽

Source Structure ◽

Polycrystalline Form ◽

Lead Halide

Lead halide perovskites possess outstanding optical characteristics that can be employed in the fabrication of phototransistors. However, due to low current modulation at room temperature, sensitivity to the ambient environment, lack of patterning techniques and low carrier mobility of polycrystalline form, investigation in perovskite phototransistors has been limited to rigid substrates such as silicon and glass to improve the film quality. Here, we report on room temperature current modulation in a methylammonium lead iodide perovskite (MAPbI3) flexible transistor made by an extremely cheap and facile fabrication process. The proposed phototransistor has the top-gate configuration with a lateral drain–channel–source structure. The device performed in the linear and saturation regions both in the dark and under white light in different current ranges according to the illumination conditions. The transistor showed p-type transport characteristics and the field effect mobility of the device was calculated to be ~1.7 cm2 V−1 s−1. This study is expected to contribute to the development of MAPbI3 flexible phototransistors.

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A 3D Lead Iodide Hybrid Based on a 2D Perovskite Subnetwork

Crystals ◽

10.3390/cryst11121570 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1570

Author(s):

Maroua Ben Haj Salah ◽

Justine Tessier ◽

Nicolas Mercier ◽

Magali Allain ◽

Antonin Leblanc ◽

...

Keyword(s):

Carbon Chain ◽

Carbon Chain Length ◽

Reference Compound ◽

Lead Iodide ◽

Direct Band Gap ◽

3D Network ◽

Intermediate Size ◽

Direct Band ◽

Halide Perovskites ◽

Lead Halide

Lead halide perovskites have emerged as promising materials for various optoelectronic applications. For photovoltaics, the reference compound is the 3D perovskite (MA)PbI3 (MA+ = methylammonium). However, this material suffers from instabilities towards humidity or light. This makes the search of new stable 3D lead halide materials very relevant. A strategy is the use of intermediate size cations instead of MA, which are not suitable to form the 3D ABX3 perovskites or 2D perovskites. Here, we report on a novel 3D metal halide hybrid material based on the intermediate size cation hydroxypropylammonium (HPA+), (HPA)6(MA)Pb5I17. We will see that extending the carbon chain length from two CH2 units (in the hydroxylethylammonium cation, HEA+) to three (HPA+) precludes the formation of a perovskite network as found in the lead and iodide deficient perovskite (HEA,MA)1+xPbxI3−x. In (HPA)6(MA)Pb5I17 the 3D lead halide network results from a 2D perovskite subnetworks linked by a PbI6 octahedra sharing its faces. DFT calculations confirm the direct band gap and reveal the peculiar band structure of this 3D network. On one hand the valence band has a 1D nature involving the p orbitals of the halide. On the other, the conduction band possesses a clear 2D character involving hybridization between the p orbitals of the metal and the halide.

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