Research progress on semiconductor perovskite solar cells

November 27, 2020

In recent years, organic-inorganic hybrid perovskite solar cells have attracted widespread attention. The material has the advantages of adjustable band gap, high absorption coefficient, long carrier lifetime and high carrier mobility. The highest efficiency reported for perovskite solar cells has exceeded 20%. Recently, academician of the Chinese Academy of Sciences and the Institute of Semiconductor Materials, Chinese Academy of Sciences Semiconductor Research Institute Wang Zhanguo's research group has made new progress in the study of perovskite solar cell carrier transport management.

The organic-inorganic hybrid perovskite material as an active layer plays a key role in cell efficiency, and simply relying on optimization of perovskite membranes to increase the efficiency of the cell has been at a bottleneck. This requires a systematic design of the battery structure for the physical process of photoelectric conversion. In this context, the team constructed a typical P–I–N structure and systematically studied the influencing factors of the generation, separation, and carrier transport and collection of photogenerated excitons in perovskite solar cells.

1, the role of the cathode work function mechanism

The difference between the work function of the electrode and the Fermi level of the active layer affects the energy band bending and the dipole moment of the interface layer, which has an important influence on the carrier transport. Using a typical inverted structure perovskite solar cell, the work function of the metal buffer layer is controlled to adjust the energy band bending at the interface of the active layer of the battery, which is favorable for electron transport and collection, thereby promoting the generation and separation efficiency of the photoexcited exciton. The research results were published on Small, and the research work was funded by the National Key Basic Research Development Program (973 Program) of the Ministry of Science and Technology.

2, carrier transport management

Efficient inverted structure perovskite solar cells are designed from the perspective of efficient separation, transport and collection of photogenerated carriers. The zirconium acetylacetonate (ZrAcac) modified Al electrode can improve the mobility of PC61BM and reduce the density of defect states. It shows that the charge transport resistance in the battery is reduced, and the electron collection efficiency of the cathode is realized. The NiOx hole is optimized by Cu doping. In the transport layer, the presence of Cu can increase the hole mobility of the NiOx layer. At the same time, the Cu doping can adjust the energy level of the NiOx to achieve the purpose of facilitating hole transport in the case of the lowest open-circuit voltage loss. The FTO glass substrate can avoid the deterioration of the anode conductivity caused by NiOx annealing, further reduce the charge transport resistance in the battery, and improve the battery fill factor. The photoelectric conversion efficiency of the battery reached 20.5%. The research results were published in Energy & Environmental Science, and the research work was funded by the National Key Basic Research Development Program (973 Program) of the Ministry of Science and Technology.

Figure 1. (a) Variation of Jph vs. Veff for different cathode work function cells, insets for the corresponding cell's Gmax values ​​(b) P(E, T) vs. Veff for different cathode work function cells, as shown in In the state of short-circuit current, P(E,T) of the corresponding battery

Figure 2. Schematic of IV curve and band structure of perovskite solar cells (left), SEM image of cross section of perovskite solar cells (right).

Stevia Rebaudioside M

Stevia Rm

Stevia Rm,Stevia Rebaudioside M,Stevia Reb-M,Rebaudioside M

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