Coordination Strategy Driving the Formation of Compact CuSCN Hole‐Transporting Layers for Efficient Perovskite Solar Cells

Abstract

The preparation of a high‐quality CuSCN thin film is very important to guarantee its efficient performance in an electronic device. Herein, a coordination strategy is reported for the formation of a highly compact CuSCN hole‐transporting layer by retarding fast crystallization via constructing intermediate adducts, and investigated its application for perovskite solar cells (PSCs). Specifically, the strong coordination bond between CuSCN and pyridine derivate ligands results in the formation of a stable intermediate phase, which is further converted to compact CuSCN layers under thermal annealing. The configuration of the intermediate phase is demonstrated to be crucial for the subsequent assembly of high‐quality CuSCN layers and results in an improved performance of the devices. CuSCN thin films crystallized from an intermediate adduct, CuSCN‐(Cl‐Py), with a rippled sheet configuration show an exceptional surface uniformity and high hole mobility, which facilitates efficient hole extraction and suppresses charge recombination in PSCs, resulting in an enhanced device efficiency of 19.19%. That is the highest value of the inverted planar PSCs using CuSCN as a hole‐transporting layer to the best of the authors’ knowledge. This novel coordination strategy can be expected to be used in the preparation of other inorganic charge transporting materials for electronic devices.

Methylammonium Compensation Effects in MAPbI3 Perovskite Solar Cells for High-Quality Inorganic CuSCN Hole Transport Layers

“…N -i-p planar PSCs conventionally use organic HEMs such as spiro-OMeTAD, poly­(triarylamine), and poly­(3,4-ethylenedioxythiophene)-poly­(styrenesulfonate) (PEDOT:PSS) to achieve high photovoltaic performance. , However, organic HEMs are relatively expansive, which may be a disadvantage for future commercialization of PSCs. Compared to organic HEMs, inorganic HEMs, such as copper­(I) iodide (CuI), copper­(I) thiocyanate (CuSCN), and NiOx, exhibit wide band gaps, high chemical stabilities, rapid hole mobilities, and low production costs. − In addition, the stability of PSCs, particularly moisture and thermal stability, have been improved by using inorganic HEMs . An ideal inorganic HEM should have the following properties: (i) chemical and thermal stability to resist the heat treatment process during the PSC manufacture, (ii) remarkable valence band alignment with the perovskite absorption layer, (iii) ability to prevent moisture from reaching the perovskite layer, and (iv) minimum absorption from the visible to near-infrared wavelength. − Furthermore, the HEM should exhibit efficient annealing conditions, such as short annealing times and low temperature, to prevent the damage of the subjacent perovskite layers.…”

Dual-functional inorganic CuSCN for efficient hole extraction and moisture sealing of MAPbI3 perovskite solar cells

“…Here, we explore the CuSCN layer's dual function as a HTM and moisture sealant and correlate it with the device performance and stability in MAPbI 3 based devices. [18][19][20][21][22] Also, the aging characteristics of efficient working devices for more than 1500 h under ambient conditions (25 AE 3 1C and 50 AE 10% RH ) without interfacial and perovskite compositional modifications are not reported. In this study, we have investigated (i) the MAPbI 3 film formation by a one-step method, without any modifications of the MAPbI 3 perovskite or charge transport layers, and the structural and morphological evolution of the devices when stored under ambient conditions for 1500 h; (ii) the device fabrication in an n-i-p configuration using an FTO/compact TiO 2 /mesoporous TiO 2 /MAPbI 3 /HTM(spiro/CuSCN/HTM free)/Au architecture; (iii) the aging of the devices at 25 AE 3 1C and 50 AE 10% RH under ambient conditions for 1500 h. CuSCN HTM based PSC devices are found to have superior stability than spiro devices without compromising on the performance.…”

Copper Bromide Hole Transport Layer for Stable and Efficient Perovskite Solar Cells

“…Inorganic p-type semiconductor HTLs have been investigated in recent years as they are stable, have high hole mobility and charge collection, and can be fabricated with simple and low-cost processes. − In particular, cuprous salts such as copper thiocyanate (CuSCN) and copper iodide (CuI) have shown promising potential to replace organic HTLs in p–i–n PSCs. − However, both CuSCN and CuI have limitations. CuSCN is a coordination polymer.…”