基于有机功能分子界面调控的杂化太阳电池及其光伏性能研究

Si/PEDOT:PSS heterojunction solar cell is attracting more and more interesting, because of its power conversion efficiency of over 12%, promising to be a novel low cost and high efficiency photovoltaic technology. But the interface contact of p-n junction is not perfect, which limits to get higher photovoltaic performance to be improved. Furthermore, there is no insight into the characteristics of interface of p-n junction. This project is that interface is engineered and modified by organic molecules to improve the power conversion efficiency of the hybrid solar cell. The functional organic molecules co-absorb onto n-type silicon surface by wet chemistry methods to realize the optimal coverage, displaying the relationship between silicon surface defect state density and organic molecular coverage ratio. The hydrophilic groups are used to improve the wetting ability of silicon surface. Based on the organic layer, the thin film of PEDOT:PSS receives the optimal coverage to realize the perfect interface of p-n junction. We choose the electron donors (alkoxy, aminoacyl, phenyl, alky) to build inversion layer (p-type) at n-type silicon surface to improve the barrier height of built-in electric field, which is controlled by function group and its position. These paths promote the photocurrent density remarkably, and other photovoltaic obviously. We investigate and understand the influence of organic structure on the minority carrier lifetime, ideality factor of p-n junction, reverse saturation current, photovoltaic characteristics , lifetime of photovoltaic device. We wish to develop and get an ideal interface based on this project, with longer minority carrier lifetime and higher barrier height, manufacturing high performance device of this Si/PEDOT:PSS heterojunction solar cell.

硅/PEDOT:PSS杂化太阳电池有望成为兼具成本和效率优势的新型太阳电池，目前效率已超过了12%，具有巨大的应用前景。但p-n结界面的接触不理想，界面特性的认识也不够，限制了光伏性能的提高。本项目拟从界面调控着手，获得较理想界面，提高电池效率。通过湿化学法共嫁接有机分子（短链、长链）实现修饰层最大覆盖率，揭示有机分子覆盖率与硅表面缺陷态密度的关联规律。利用亲水基团改善硅表面的润湿性，使得PEDOT:PSS薄膜完全覆盖表面，形成较理想界面。通过给电子官能团及其位置异构调控内建电场势垒高度，并探索给电子基团在n型硅表面形成反型层（p型）增强内建电场的机理。通过上述对界面态和势垒的调控研究，深入理解有机分子对少子寿命、p-n结理想因子、反向饱和电流、电池光伏性能和寿命的影响。本项目的成功实施可望加深界面修饰和内建电场势垒的调控理论的认识，并获得较理想异质结界面，制备出高效稳定的电池器件。

硅/PEDOT:PSS杂化太阳电池有望成为兼具成本和效率优势的新型太阳电池，目前效率已超过了12%，具有巨大的应用前景。但p-n结界面的接触不理想，界面特性的认识也不够，限制了光伏性能的提高。通过湿化学方法，采用热引发的氢化硅烷化反应实现有机分子的共嫁接，在硅表面嫁接醌氢醌（BQ）、醇溶性聚[9,9-二(3'-(N,N-二甲胺基)丙基)-2,7-芴]-交-2,7-(9,9-二辛基芴)](PFN)、聚氧化乙烯（PEO）等，分析各有机分子的化学吸附行为，并分析嫁接工艺参数，确立最佳的工艺路线。分析有机分子修饰层对硅表面润湿性的影响，揭示润湿性与PEDOT:PSS薄膜覆盖率的关联规律。研究界面修饰层对内建电场势垒高度的调控机理，结合实验拟合数据和理论计算结构，分析并确立势垒高度变化规律。研究有机单分子层的覆盖率及其官能团对硅表面态密度的影响。研究电池内建电场势垒高度和硅表面态密度对少数载流子及扩散速率的影响，分析有机分子钝化修饰对少子寿命、复合速率、电池光伏特性和寿命等参数影响规律，结合内建电场势垒高度差、硅表面缺陷态密度等测试结果进行分析讨论。晶硅/PEDOT:PSS杂化太阳电池的效率超过15%。本项目的成功实施加深界面修饰和内建电场势垒的调控理论的认识，并获得较理想异质结界面，制备出高效稳定的电池器件。