Composite Hole‐Transport Materials Based on a Metal‐Organic Copper Complex and Spiro‐OMeTAD for Efficient Perovskite Solar Cells

Abstract

Spiro‐OMeTAD has been the most commonly used hole‐transport material in perovskite solar cells. However, this material shows intrinisic drawbacks, such as low hole mobility and conductivity in its pristine form, as well as self‐aggregation when deposited as thin film. These are not beneficial properties for efficient hole transport and extraction. In order to address these issues, we have designed a new type of composite hole‐transport materials based on a new metal‐organic copper complex (CuH) and Spiro‐OMeTAD. The incorporation of the molecularly bulky HTM CuH into the Spiro‐OMeTAD material efficiently improves the hole mobility and suppresses the aggregation in the Spiro‐OMeTAD film. As a result, the conversion efficiencies obtained for perovskite solar cells based on the composite HTM system reached as high as 18.83%, which is superior to solar cells based on the individual hole‐transport materials CuH (15.75%) or Spiro‐OMeTAD (14.47%) under the same working conditions. These results show that composite HTM systems may constitute an effective strategy to further improve the efficiency of perovskite solar cells.

Fluorine‐Substituted Benzotriazole Core Building Block‐Based Highly Efficient Hole‐Transporting Materials for Mesoporous Perovskite Solar Cells

“…However, the complicated synthesis procedures and low yield of Spiro‐OMeTAD make its price very expensive, triggering the researchers over the world to search for/develop efficient and low‐cost alternative HTMs. To date, many alternative HTMs constructed with different conjugated core units, such as phenothiazine, thiophene, phenoxazine, silolothiophene, triazines, and tetraphenylethene, have been reported . Benzotriazole (BTA) is a cheap and commercially available material, which has been widely used in designing sensitizers for dye‐sensitized solar cells by reason of the outstanding electron‐accepting property.…”

High‐Performance Inverted Planar Perovskite Solar Cells Enhanced by Thickness Tuning of New Dopant‐Free Hole Transporting Layer

“…As literatures reported, HTMs can be mainly divided into two types based on their chemical structures. One is that those containing rigid spiro units as cores (such as sprio‐type fluorine, triptycene, and their derivatives), another one is those containing planar units as cores (such as thiophenyl, truxene, phthalocyanine units and other π‐conjugated units, and so on). However, both HTMs have their advantages and limitations.…”

Bis[di(4-methoxyphenyl)amino]carbazole-capped indacenodithiophenes as hole transport materials for highly efficient perovskite solar cells: the pronounced positioning effect of a donor group on the cell performance

“…When Spiro-OMeTAD was coated onto the perovskite surface, some observable large particles formed on the film, which can significantly decrease the device performance and stability of Spiro-OMeTAD-based PSCs devices. [56][57][58] We further examined the hydrophobic properties of YK1, YK2 and Spiro-OMeTADcoated thin films. As shown in the Figure 7b, the contact angles of water on YK1 and YK2 film is 102° and 95°, respectively, thus the hydrophobic nature of YK1 and YK2based HTMs can efficiently prevent the moisture penetration into the perovskite layer.…”

“…By considering the fact that all PSCs devices contain the same TiO 2 /perovskite interface, the R ct is mainly dominated by the HTL/perovskite interface. 56,59 Generally, a lower R ct indicates much more efficient charge transfer at the interface in the device. The R ct value, which was obtained from by fitting the EIS spectra using the equivalent circuit model, follows the order YK2 (62.5 Ω) > Spiro-OMeTAD (46.4 Ω) > YK1 (38.2 Ω).…”