Development Of High-Throughput Materials Calculation Method And Its Application In Design Of Semiconducting Optoelectronic Materials

Optoelectronic semiconductors play a crucial role for the application in energy conversion and optoelectronic devices,such as transistors,light-emitting diodes,solar cells,sensors etc.Whereas the commercialized inorganic-semiconducting optoelectronic materials,e.g.,crystalline silicon,GaN etc.are not low-cost due to their complex preparation process.Therefore,promises of potential semiconducting optoelectronic materials include the low-cost and convenient assembly process as well as the tunable properties.However,the main issues are the low efficiency and high-cost of the conventional "trial and error" approach to screen the potential candidates from a huge of materials space determined by chemical composition,structure as well as synthesized condition.Fortunately,technological of computational simulation assisted by sophisticated materials calculation methods show efficiently to explore novel materials,which is low-cost and high-efficiency.Therefore,it's crucial to develop efficient method for screening functional materials.In this thesis,we develop a tool for high-throughput materials calculation.Worth note that halide perovskites and two-dimensional materials are low-cost and can be easily processed and tuned conveniently by using variable approaches.Thus,we design a series of semiconducting optoelectronic materials based on halide perovskites and two-dimensional materials,and systematically investigate their optoelectronic properties.Our findings are as follows:1.We developed a useful tool named JUMP2(Jilin University Materials-design Python Package)for high-throughput materials calculations.Ones can create of calculation workflows,manage of large amounts of calculations,extract of calculated results,and post-process analysis by using this open-source Python infrastructure designed for large-scale high-throughput energetic and property calculations of functional materials.This free and open-source tool has been registered for intellectual property protection,and be open for domestic counterparts.2.We exploited the strategy of "cation-transmutation" to design halide perovskites,and found a series of stable Pb-free double perovskites,offering a new routine for the design of stable Pb-free solar cells.The idea is to convert two divalent Pb2+ into one monovalent M(I)and one trivalent cation M(III),forming a rich class of quaternary halides in double perovskite structure A2M(I)M(III)X6.By using the first principle of high-throughput calculation,we screened more than one hundred of candidate materials with photovoltaic-functionality-directed principle.Finally,we indentify 17 optimal Pb-free materials with intrinsic thermodynamic stability,suitable band gaps,small carrier effective masses,and low excitons binding energies as promising candidates to replace Pb-based photovoltaic absorbers in perovskite solar cells.Among them,Cs2AgBiCl6,Cs2AgSbCl6,Cs2AgInCl6 have been synthesized recently.The chemical trends of phase stabilities and the electronic properties are also established with respect the evolution of chemical components.Our findings would offer useful guidance for development and fabrication of non-toxic and stable perovskite solar materials.3.We revealed the factors associated with the thermodynamically peeling process of two-dimensional layers,and found that stacked superlattices by using two dimensional layers present flexibly tunable indirect-/direct-gap values.We found interlayer interaction in studied layered materials reflects not only by van der Waals interaction,but also by weak covalent bonds and long-range Cloumb interaction.The inplane strain can efficiently result in decrement of peeling energy.Besides,binary superlattices stacked by transition metal dichalcogenides(TMDCs)show type ? band structure,in which electrons and holes are distributed in different layers.Importantly,their bandgap values can be continuously tuned by varying the proportion of TMDCs,in which the superlattices could undergo transition from indirect bandgap to direct band gap.This is due to inplane strain because of the lattice mismatch.Moreover,large lattice mismatch and band offset lead to the transformation from semiconductor to metal.Our findings may be useful for optimizing the exfoliation process,indentifying compounds with weak interaction and provide a desirable approach for producing nano-device base on two-dimensional materials.