Phase-Pure Layered Perovskite Films for Photodetectors with Enhanced Performance and Stability

Abstract

Organic–inorganic hybrid perovskites have attracted intense interest in solution-processable optoelectronic devices, while reduced dimensional perovskites with layered structures show a widely tunable band gap and superior environmental stability. Controlled synthesis of phase-pure layered perovskites, especially in the form of polycrystalline films, is crucial to improve the overall performance of perovskite-based devices. Here, we report a facile method to fabricate phase-pure layered perovskite films by the addition of a poor solvent during the spin-casting process. The use of these perovskites as active layers in photodetectors shows enhanced detection capability and stability. It is found that the kinetics of nucleation and crystallization processes is the key factor in controlling the phase purity of layered perovskites, and the introduction of the poor solvent elevates the supersaturation level of the precursor solution to form kinetic-controlled products. Moreover, the high phase purity significantly reduces the pinholes in polycrystalline films, which is beneficial for the efficient charge separation of photogenerated electron–hole pairs. As a result, the photodetectors based on phase-pure perovskites show a superior responsivity of 12.7 mA W–1 excited at the corresponding absorption band, which is enhanced by 1 order of magnitude compared with those based on as-cast perovskites. Meanwhile, the stability of photodetectors is significantly improved, in which the photocurrent shows only ∼20% decrease after exposure to excitation light or ambient environment for a long period of time.

Improve Perovskite Solar Cell Stability and Efficiency via Multifunctional Multiple‐Ring Aromatic Dopant Passivation

“…[10,12] These unavoidable surface and boundary defects during the manufacturing process [13] severely restrict the further development of PSCs applications. [14] In addition, due to the existence of CH 3 NH 3 þ (MA þ ) cations with hygroscopic properties, [15,16] the long-term stability of devices using MAPbI 3 as the absorbent layer is poor, and they are effortless to decompose under conditions such as exposure to air, heat, and light. Therefore, passivating defects to decrease energy loss and improve the environmental stability of devices has become an urgent problem.…”

Synthesis of Cs+-Tuned (PEA)2PbI4 Perovskite Thin Films by One-Step Spin Coating

“…Presently, it has been successfully applied in light-emitting diodes, solar cells, photoelectric detectors and other new photoelectric devices. [8][9][10][11][12][13][14][15][16] In organic-inorganic hybrid perovskite materials, when the A-site cations are macromolecular organic cations with hydrophobicity, it usually has an organic-inorganic-organic alternating layered twodimensional (2D) structure due to the formation of the organic layer of macromolecules, which is different from the three-dimensional (3D) crystal structure of the all-inorganic perovskite. [17][18][19] Therefore, unlike the all-inorganic perovskite or other materials with high humidity response, 20 the moisture resistance of 2D perovskite can be improved to some extent.…”