A Cu₂O–CuSCN Nanocomposite as a Hole-Transport Material of Perovskite Solar Cells for Enhanced Carrier Transport and Suppressed Interfacial Degradation

Abstract

Interfacial degradation in perovskite solar cells is a critical issue affecting long-term stability for future commercialization. In particular, a perovskite and an organic hole-transport layer (HTL) react easily when the device is exposed to extreme operating conditions (heat, light, and air). To prevent degradation, an inorganic CuSCN HTL has emerged as an alternative, yet the interfacial reactivity is still not clearly elucidated. Herein, Cu 2 O and CuSCN are coutilized to form an efficient and stable HTL. While uniform film formation using Cu 2 O is difficult despite its high mobility, a Cu 2 O− CuSCN nanocomposite can be excellently synthesized as an effective HTL, exhibiting a power conversion efficiency (PCE) of 19.2% and sustaining its PCE over 90% for 720 h under extreme conditions (85 °C/85% of relative humidity, encapsulated). A chemical distribution analysis by secondary-ion mass spectroscopy (SIMS) suggests that a Cu 2 O nanoparticle layer protects the interface between the perovskite and CuSCN. The optoelectronic properties of the nanocomposite HTL and the improved solar cell performance are correlated with the recombination rate, electronic trap distribution in the band gap, and charge extraction efficiencies.

Stability of Perovskite Solar Cells: Degradation Mechanisms and Remedies

“…Compositional engineering of the perovskite has primary importance (Kim et al, 2019a;Matsui et al, 2019). Several reports are available where highly stable devices are achieved by the modification of the charge-transporting layer or by modifying the interface by a stabilizing or hydrophobic material (Kim et al, 2019b;Lee et al, 2019;Agresti et al, 2020;Kim et al, 2020b;Kumar et al, 2020). Metal electrodes have been replaced by a carbon electrode that is water resistant and can improve stability (Wu et al, 2019c).…”

Properties and Applications of Copper(I) Thiocyanate Hole‐Transport Interlayers Processed from Different Solvents

“…A mixture of both may result in a cascaded hole injection/extraction interface, provided that a favorable composition gradient can be formed normal to the film plane. Such a Cu 2 O/CuSCN composite HTL has already been used in perovskite solar cells to enhance charge transport and inhibit interfacial degradation, [ 49 ] but with different processing methods from us. Therefore, further investigations are needed to explore the origin and applications of this effect.…”

Promotion Strategies of Hole Transport Materials by Electronic and Steric Controls for n–i–p Perovskite Solar Cells

“…For example, Cu 2 O and CuSCN were integrated to form an efficient and stable hybrid HTL (Figure 7 e). [113] On the one hand, film morphology of single Cu 2 O layer was difficult to be uniform, despite its high hole mobility; on the other hand, the anion of CuSCN is chemically active with the underlying perovskite and the above electrode, causing instability issues. To solve these problems, a Cu 2 O/CuSCN nanocomposite can be excellently synthesized as an effective HTL, fabricating n–i–p PSCs with PCE of 19.2 % and high stability (which sustained its PCE over 90 % after 720 h aging under extreme conditions at 85 °C/85 % of relative humidity, encapsulated).…”