The ion migration induced by the electric field, heat, and light illumination also contributes to the hysteresis in J–V curves 13, 14, which in turn leads to poor long-term stability resulted from significant structural changes, including the lattice distortion and the phase decomposition. In fact, with increasing temperature, visible diffusion of iodine initiates at a temperature below 150 ☌ and lead migration is induced at a higher temperature around 175 ☌, causing the degradation of perovskite and formation of PbI 2 6. It has been reported that the perovskites rapidly degrade under increased temperature 6, oxygen 7, moisture 8, and UV light illumination 9, often due to the structure instability caused by electromigrations 10, ion migration, 11 and interfacial relationships 12. Despite the great progress in increasing the device PCE from initial 3.8% 4 to the most recent 23.3% 5 in just one decade, the commercialization of this technology remains hindered by the stability issues of materials. Solar cells based on organic–inorganic hybrid perovskites (CH 3NH 3PbI 3, MAPbI 3) have attracted widespread research attention due to their low synthesis cost and high-power conversion efficiency (PCE) 1, 2, 3. The structural evolution during decomposition process also sheds light on the structure instability of organic–inorganic hybrid perovskites in solar cell applications. These findings impose important question on the interpretation of experimental data based on electron diffraction and highlight the need to circumvent material decomposition in future electron microscopy studies. We propose a decomposition pathway, initiated with the loss of iodine ions, resulting in eventual collapse of perovskite structure and its decomposition into PbI 2.
We find that MAPbI 3 is very sensitive to the electron beam illumination and rapidly decomposes into the hexagonal PbI 2.
Here, we investigate the structure instability of the single-crystalline CH 3NH 3PbI 3 (MAPbI 3) film by using transmission electron microscopy. Many efforts have been made to study their structures in the search for a better mechanistic understanding to guide the materials optimization. Organic–inorganic hybrid perovskites are promising candidates for the next-generation solar cells.
0 kommentar(er)
