Chinese Academy of Sciences made new progress in solar photovoltaic cell research
Solar photovoltaic cells based on organic molecules, as the most potential alternative to traditional high-consumption single crystal solar devices, have received widespread attention in recent years. Organic molecules have high extinction coefficients and no organic molecule-based solar photovoltaic cells have received widespread attention in recent years as the most potential replacement for traditional high-consumption single crystal solar devices. Organic molecules have the advantages of high extinction coefficient, non-toxicity, easy synthesis, and low price. At present, this type of battery has an energy conversion efficiency of more than 13% (under 50% sunlight) and long-term stability. Although a large number of experimental studies have revealed various macroscopic properties of organic molecular solar photovoltaic cells, such as volt-ampere characteristics, spectra, thin film morphology, etc., images on the interface structure of organic molecules and energy conversion mechanisms on the microscopic scale are still lacking. This prevents people from further improving the performance of solar photovoltaic cells. Researchers Jiao Yang, Zhang Fan, Ding Zijing, and Meng Sheng, Ph.D. students from the Surface Laboratory of the Institute of Physics, Chinese Academy of Sciences / Beijing National Laboratory for Condensed Matter Physics have recently made detailed theoretical and experimental studies on the mechanism of solar cells based on organic molecules. Using time-dependent density functional theory simulations containing excited state information, they found that the energy level of the molecule at the TiO2 interface is modulated by the vibration of the interface chemical bonds, which directly affects the dynamics and efficiency of excited state electron injection into the semiconductor. "Phys. Chem. Chem. Phys. 13, 13196 (2011) ". Next, they collaborated with Dr. Ren Jun of Tsinghua University and Professor E. Kaxiras of Harvard University to analyze the atomic structure and electronic coupling of C60 / CuPc, a typical interface of organic solar energy. They found that different molecular arrangements (horizontal or vertical) at the interface have little effect on solar absorption, but they have an important effect on the arrangement of electron energy levels. Among them, the molecular energy levels of the two layers of the horizontally arranged C60 / CuPc interface are closer, which provides a voltage higher than the vertically arranged interface by about 0.3V. This has an important impact on improving solar energy conversion efficiency. The results were published in "NanoResearch 5,248 (2012)". They further studied the effect of the atomic structure of metal-free pure organic molecules at the TiO2 interface on the efficiency of the formed organic dye solar cells. Such molecules generally adopt the structure of Donor-Ï€-Acceptor, most of which are bound to the surface through cyanoacrylic groups. Although this type of molecule has been widely used, its adsorption structure is not clear. Previously, it was generally believed that this type of organic dye was similar to the traditional ruthenium complex dye, only adsorbed on the surface of TiO2 through the carboxyl group. Based on first-principles molecular dynamics and time-dependent density functional theory calculations, Jiao Yang and the Swiss Federal Institute of Technology Professor Michael Graetzel cooperated to study the adsorption and adsorption of organic molecules containing cyanopropene groups on the surface of anatase TiO2 (101) Electronic dynamics (Figure 1). Through detailed analysis of the vibration spectrum obtained from the dynamic simulation and comparison with the infrared absorption spectrum obtained from the experiment, they found that the cyano group and the carboxyl group participate in the surface adsorption together, and this adsorption configuration is very conducive to the conversion of solar energy. Colored Binder Clips, Black Binder Clips, Metal Binder Clip, Small Binder Clips JNY International Trade Co., Ltd , http://www.jny-stationery.com