Insights into the Influence of Work Functions of Cathodes on Efficiencies of Perovskite Solar Cells

Abstract

Though various efforts on modification of electrodes are still undertaken to improve the efficiency of perovskite solar cells, attributing to the large scope of these methods, it is of significance to unveil the working principle systematically. Herein, inverted perovskite solar cells based on indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/CH NH PbI /phenyl-C61-butyric acid methyl ester (PC BM)/buffer metal/Al are constructed. Through the choice of different buffer metals to tune work function of the cathode, the contact nature of the active layer with the cathode could be manipulated well. In comparison with the device using Au/Al as the electrode that shows an unfavorable band bending for conducting the excited electrons to the cathode, the one with Ca/Al presents a dramatically improved efficiency over 17.1%, ascribed to the favorable band bending at the interface of the cathode with the active layer. Details for tuning the band bending and the corresponding charge transfer mechanism are given in a systematic manner. Thus, a general guideline for constructing perovskite photovoltaic devices efficiently is provided.

Synergistic Interface Energy Band Alignment Optimization and Defect Passivation toward Efficient and Simple‐Structured Perovskite Solar Cell

“…In theory, the former requires that the WF of TCO is smaller than that of perovskite, i.e., WF TCO < WF perovskite , and the latter needs that the CBM of perovskite should be much closer to the E F of TCO. In fact, previous work has suggested that the WF of cathode has a great influence on the performance of planar device …”

Stability and Performance of Nanostructured Perovskites for Light‐Harvesting Applications

“…And lastly different methods for optimizing the alignment of the energy bands of the used materials should be considered to further improve the cells performance. Promising candidates are the inclusion of buffer layer to bridge the gap between two bands, the doping of charge carrier transport layers and the perovskite itself to enhance charge carrier injection and mobility and the adjustment of the perovskites energy bands by changing its chemical composition …”

X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells

“…Organic electronic devices are becoming increasingly commercially viable due to their continuously improving efficiency in the recent years and the tremendous amount of research targeted in maintaining relatively high efficiencies along with their low cost of production and technological ease of transfer. [1,2] The recently recorded high efficiencies of these devices [3][4][5][6][7] are still well below the theoretical maximum efficiencies. [8] It is now well known that to improve the performance of these devices it is imperative to have a thorough the anode is made of organic materials (polymers, small molecules), of graphene oxide [9] or even of inorganic material like NiO.…”