利用摻雜錳於二維層狀鈣鈦礦提升激子磁光效應

Abstract

有機-無機鈣鈦礦因為其良好的光電特性，使得鈣鈦礦材料在各個光電領域上均有突出的表現，除了最受矚目的太陽能電池的能源轉換效率從3.8%提升至25.2%，以及常見的發光二極體、光感應器、雷射等應用外，近年來，鈣鈦礦也逐漸踏入了磁光領域中，利用其良好的吸收係數與較大的原子序和半徑的鉛離子所引起的自旋軌道耦合產生的能階分裂，使鈣鈦礦在磁場下，對於左右旋偏振光有不同的吸收度與折射率，進而產生磁光效應。本篇將摻雜錳離子於材料內以增強磁光效應。成功將合成出二維鈣鈦礦晶體BA2PbI4 (n=1)與BA2MAPb2I7 (n=2¬)，以摻雜錳離子的方式製作成Mn-doped BA2PbI4 (n=1)與Mn-doped BA2MAPb2I7 (n=2¬)，利用粉末X光繞射鑑定結構與測量吸收光譜確定能隙發現結構與能隙皆與無摻雜晶體相同，特別的是在放射光譜中，因為磁場的影響，增強了雷射激發後所產生的放射光，而無摻雜錳離子之晶體則沒有這個現象發生。最後透過測量磁性圓二色性，確實在Mn-doped BA2PbI4製作成的元件中，訊號會受到錳離子產生的內部磁場影響，有部分增強，也有部分減弱，但在零磁場的情況下，可以明顯看出訊號增強將近六倍，最後也利用外加電場達到控制磁性圓二色性訊號，進而增加材料的應用性。未來將有機會合成出更高層數的鈣鈦礦，實現涵蓋可見光區域之錳摻雜二維鈣鈦礦，使材料在光學應用上更加廣泛。

Organic-inorganic perovskites have outstanding performance in various optoelectronic fields due to their good photoelectric properties, except for the most eye-catching solar cell energy conversion efficiency increased from 3.8% to 25.2%, and light-emitting diodes, light sensors, lasers, etc. In recent years, perovskites have gradually entered the field of magneto-optics, their good absorption coefficient, large atomic order and large radius of lead ions cause the spin-orbit coupling. This coupling makes the perovskite energy-level splitting. And under a magnetic field, the perovskite has different absorption and refractive index for left and right polarized light, which in turn produces a magneto-optical effect.In this article, manganese ions will be incorporated into the material to enhance the magneto-optical effect. We successfully synthesized two-dimensional perovskite crystals BA2PbI4 (n=1) and BA2MAPb2I7 (n=2), and produced Mn-doped BA2PbI4 (n=1) and Mn-doped BA2MAPb2I7 (n=2) by doping with manganese ions, using powder X-ray diffraction to identify the structure and measuring the absorption spectrum to identify the energy gap, it is found that the structure and energy gap are the same as those of undoped crystals. Especially in the emission spectrum, because of the influence of the magnetic field, the laser excitation is enhanced. And there is no enhancement in undoped crystals Finally, by measuring the magnetic circular dichroism, it is true that in the components made of Mn-doped BA2PbI4, the signal will be affected by the internal magnetic field generated by manganese ions, some of which are strengthened and some are weakened. In the case of zero magnetic field, it can be clearly seen the output signal is nearly six times stronger. The external electric field is also used to control the magnetic circular dichroism signal and increase the applicability of the material.In the future, there will be opportunities to synthesize higher layers of perovskite, realize manganese-doped two-dimensional perovskite covering the visible light region, and make the material more widely used in optical applications.