Quantum Transport Simulation Of All-In Organic Perovskite Optoelectronic Devices

The organic-inorganic hybrid perovskite has become one of the most popular materials in the area of photovoltaic materials,because of its designable structure,adjustable electronic and optical properties,and long carrier lifetime.Unfortunately,the lattice of the hybrid perovskite is not stable under a high temperature or humidity environment.In contrast,the metal cesium atoms of all-inorganic perovskite CsPbX3(X=I,Br,Cl)have replaced the volatile organic compounds to make it have higher thermal stability,and some evidence shows it can perform equally excellently.Therefore,the all-inorganic perovskite is rapidly becoming an ideal alternative material and attracting the attention of the researchers.Among several all-inorganic lead halide perovskites,the cubic phase CsPbI3 successfully stand out because it has a band gap(1.73 eV)better than other similar materials,making it the most attractive candidate for photovoltaic applications.On the other hand,because of the atomically uniform thickness,smooth surface,and good flexibility of two-dimensional(2D)materials,more attention has been moved to the 2D perovskite.The researchers hope that 2D perovskite can combine 2D materials and perovskite materials to obtain better performance.Throughout the previous research on 2D all-inorganic perovskite materials is just in their infancy,and most researchers focus on their photoelectric properties.Given the high potential of 2D all-inorganic perovskites-based devices,a theoretical study on the intrinsic carrier transport properties in the device configuration is desired to further improve the device performance.To study the carrier transport behavior of 2D CsPbI3,we used the first ab initio quantum transport simulation to simulate the performance of transistors based on a 2D monolayer(ML)Cs2PbI4 in the sub-10 nm range.The research is mainly divided into the following two aspects,one is to study the structure and electronic properties of ML Cs2PbI4,the other is to study the performance limits of sub-10 nm field-effect transistors(FETs)based on ML Cs2PbI4 as the channel material.Based on first-principles calculations,we know that 2D ML Cs2PbI4 not only has a direct bandgap of 1.61 eV but also has an efficient light absorption performance with an absorption coefficient of up to 105.Compared with other all-inorganic lead halide perovskites,it shows excellent photoelectric performance.The results show that the performance of the n-type transistor is much better than that of the p-type transistor under the same conditions.The on-currents of the DG ML Cs2PbI4 MOSFETs range from 97 to 1869 ?A ?m-1 as the gate length and the bias increased.Good gate electrostatics with a subthreshold swing(SS)decreases from 263 to 91 mV dec-1 is observed.In comparison to MoS2,the DG ML Cs2PbI4 MOSFETs can achieve up to seven times greater on-state current at the gate length of 9 nm.Moreover,the delay time(?)of Cs2PbI4 MOSFETs are also superior to those of MoS2 due to the small effective mass of the electrons.Compared with the International Technology Roadmap for Semiconductors(ITRS)2015 requirements for high performance(HP)devices,the sub-10 nm perovskite transistors show much lower power-delay products(PDP)and much less delay time(except at Vb=0.40 V),indicating the high promise of Cs2PbI4 for low-power applications.