A new mechanism for improving the efficiency of solar cells by the ferroelectric effect has been revealed

Recently, Academician Li Can, Dr. Qin Wei and PhD student Wajid Ali of Dalian Institute of Chemical Physics, Chinese Academy of Sciences have made new progress in the field of organolead-halide perovskite (MHP) solar cell research. The team revealed the correlation between the non-radiative composite of perovskite materials and lattice strain, and made the open-circuit voltage of solar cells close to the thermodynamic limit by regulating the iron bullet strain. The results were published in Nature Communications.

Schematic diagram of the mechanism (Photo courtesy of Dalian Chemical Institute)

While studying the synthesis of solar fuels such as photocatalysis (electro)catalysis, Li Can’s team has long explored new materials and mechanisms of solar cells, and has also made important achievements in the research of basic scientific problems of organic solar cells and perovskite solar cells, and proposed that Dion-Jacobson two-dimensional phase perovskites can significantly improve the performance and stability of perovskite cells.

In this work, the team used the coupling of MHP phase transition process and crystallization process to prepare perovskite iron projectiles that are stable at room temperature by inducing anisotropic symmetry breaking. Under an applied electric field, the electrostrictive properties of ion crystals cause iron elastic strain on MHP. This work found that the non-radiative recombination of photogenerated carriers in MHP is significantly suppressed under iron bomb strain. By finely characterizing the crystal structure under iron bullet strain, the researchers established a correlation between the iron bomb strain and non-radiative recombination of MHP.

Subsequently, combined with theoretical calculations, it is revealed that the iron bullet strain will cause the ferroelectric phase transition of the domain wall unit cells, and the ferroelectric lattice electric field will be aligned under the action of the external electric field to form a stable charge separation ability. By inducing the iron bullet strain, the charge separation ability of the ferroelectric field can increase the open-circuit voltage of MHP solar cells by about 150 mV to 1.26 V, which is close to the thermodynamic limit of the material (1.32 eV).

The above results provide new key evidence for the ferroelectric field formation mechanism of MHP materials. (Source: Sun Danning, China Science News)

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