Double Perovskite Solar Cells

基于混合卤化物钙钛矿材料的太阳能电池是历史上增长最快的太阳能技术，2009年的起点效率为3%，现在已超过22%；已经可以与多晶硅等行业标准相媲美。然而，尽管效率有了相当大的飞跃，但主要的担忧之一尚未得到决定性的解决：该结构的毒性。近年来，以铋(III)为基础的化合物和Ci(I)化合物等替代无铅结构被引入作为有前途的材料，但它们的光电性能并不是很理想，由此产生的器件效率低下。在这里，学生将瞄准新的“双”钙钛矿结构。这一新引入的材料家族是基于用两种不同的元素取代铅中心，首先是占据八面体交替中心的Bi3+和Ag+1，从而导致具有立方对称性的有序双钙钛矿结构。初步结果表明，这些结构显示出很强的光致发光，寿命在几十纳秒量级，这意味着光激发物种寿命长，陷阱密度低，适合于应用于太阳能电池。

Solar cells based on hybrid halide perovskite materials are the fastest growing solar technology in history, with starting point efficiencies of 3% in 2009 and now surpassing 22%; already comparable to industry standards such as poly-Si. However, despite the rather large leaps in efficiency, one of the main concerns has yet to be decisively addressed: the toxicity of the structure. Alternative lead-free structures in the forms of Bi(III) based compounds and Ci(I) compounds have recently been introduced as promising materials, yet their optoelectronic properties are suboptimal and the resulting devices are inefficient. Here the student will target new "double" perovskite structures. This newly introduced family of materials is based on the substitution of the lead centre with two different elements, initally Bi3+ and Ag+ 1 which occupy alternating centres of the octahedra, thus leading to an ordered double perovskite structure with cubic symmetry. Initial results show that these structures exhibit strong photoluminescence with lifetimes in the order of tens of nanoseconds, implying that photoexcited species are long-lived and trap densities are low, making them suitable for incorporation into solar cells.