Recently, Li Xinhua, research group of the Institute of Solid State Physics, Hefei Institute of Material Science, Chinese Academy of Sciences, and Dai Jianming's research group have made new progress in the field of perovskite solar cells, and developed a new type of high-efficiency perovskite solar energy without organic electron transport layer. The battery, related research published in the journal Advanced Materials magazine Solar RRL (DOI: 10.1002/solr.201800167).
As an indispensable part of new energy sources, the research progress of photovoltaic energy has attracted much attention. Among them, perovskite solar cells have superior light absorption characteristics, adjustable band gap, long carrier lifetime and high mobility. The invention has the advantages of simple preparation process, low cost and the like, and has wide application prospects, and has become a research hot spot in the field of photovoltaics.
Perovskite solar cells are divided into two types: formal (nip) and trans (pin), and trans (pin) planar structure perovskite solar cells (anode/hole transport layer/perovskite/electron transport layer/ Cathode metal) has attracted more and more attention due to its simple preparation process, low temperature film formation and no obvious hysteresis effect. However, it still faces many problems: First, the photoelectric conversion efficiency is still insufficient; Second, it is used as perovskite ( Such as: methylamine lead iodine (MAPbI 3)) The core component of the solar cell, the organic electron transport layer (such as C60, fullerene such as PCBM and its derivatives) has poor thermal stability and cannot block the metal electrode at MAPbI. 3The diffusion in the middle; the third is the expensive cost of the organic electron transport layer.
In order to solve these problems, solid researchers used titanium (Ti) instead of organic electron transport layer to design a perovskite solar cell (ITO (anod transparent conductive glass) / PTAA (organic hole transport layer) as shown in Figure 1. ) /MAPbI 3/Ti/Cathode (cathode metal) structure. Studies have shown that the Ti (10nm) layer prepared by the high viscosity of Ti can completely cover the surface of the perovskite, which is beneficial to reduce the electrode contact resistance and can be effective. Inhibits the diffusion of the cathode metal in the perovskite device, thereby helping to protect the structural integrity and stability of the device; on the other hand, in Ti and MAPbI 3At the interface, Ti forms a Ti-N bond with methylamine ion (MA+), which inhibits MAPbI 3The decomposition caused by the volatilization of the surface layer MA+ further improves the stability of the device (Fig. 2). The results show that the photoelectric conversion efficiency of the perovskite cell prepared by using Ti as the electron transport layer has reached 18.1% (Fig. 3). This is the highest efficiency achieved by the direct contact between the metal material and the perovskite layer, and is also the photoelectric conversion efficiency of the perovskite solar cell comparable to the conventional PCBM as the organic electron transport layer. Moreover, compared with the preparation conditions of the organic electron transport layer The preparation and cost of the Ti layer is simpler and cheaper.
This research work provides a new idea for constructing efficient perovskite solar cells and has very important guiding significance.
The work was funded by the National Natural Science Foundation of China and the National Natural Science Foundation of China.
Figure 1. Trans ITO/PTAA/MAPbI
3Schematic diagram of perovskite device of /Ti/Cathode structure
Figure 2. MAPbI
3Schematic diagram of interface Ti-N bonding in /Ti
Figure 3. Current-voltage diagram of a different perovskite device with a cathode metal
