Low‐Temperature Solution‐Processed CuCrO₂ Hole‐Transporting Layer for Efficient and Photostable Perovskite Solar Cells

Abstract

Organic–inorganic hybrid perovskite solar cells (PVSCs) have become the front‐running photovoltaic technology nowadays and are expected to profoundly impact society in the near future. However, their practical applications are currently hampered by the challenges of realizing high performance and long‐term stability simultaneously. Herein, the development of inverted PVSCs is reported based on low temperature solution‐processed CuCrO2 nanocrystals as a hole‐transporting layer (HTL), to replace the extensively studied NiOx counterpart due to its suitable electronic structure and charge carrier transporting properties. A ≈45 nm thick compact CuCrO2 layer is incorporated into an inverted planar configuration of indium tin oxides (ITO)/c‐CuCrO2/perovskite/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM)/bathocuproine (BCP)/Ag, to result in the high steady‐state power conversion efficiency of 19.0% versus 17.1% for the typical low temperature solution‐processed NiOx‐based devices. More importantly, the optimized CuCrO2‐based device exhibits a much enhanced photostability than the reference device due to the greater UV light‐harvesting of the CuCrO2 layer, which can efficiently prevent the perovskite film from intense UV light exposure to avoid associated degradation. The results demonstrate the promising potential of CuCrO2 nanocrystals as an efficient HTL for realizing high‐performance and photostable inverted PVSCs.

Enhancing Efficiency and Stability of Photovoltaic Cells by Using Perovskite/Zr‐MOF Heterojunction Including Bilayer and Hybrid Structures

“…It should be noted that the optical properties of both UiO‐66 and MOF‐88 are quite suitable for applications in PVSCs since they might provide a down‐conversion of high‐energy photons for the perovskite film . As seen, their intense absorption in the UV region can help filter the UV radiation, which has been cited to be harmful for perovskite materials.…”

“…Therefore, besides the improved absorption of perovskite layer or the interference effects, the energy transfer between MOF and perovskite might also be considered (Figure c,d), particularly for the case of UiO‐66 that showed intense UV absorption and PL emission (Figure S5a, Supporting Information). It definitely warrants more in‐depth investigation in the future but this result reveals that using MOF as the interlayer at the light incoming side might possess potential advantage of converting the UV radiation to simultaneously increase the photocurrent and UV stability of the derived devices …”

Dopant‐Free Hole Transporting Materials for Perovskite Solar Cells

“…The CuCrO 2 HTL was also enabled to inhibit the UV‐induced decomposition of perovskite, allowing a significant improvement of device photostability. Improved crystallinity of the perovskite film grown on the CuCrO 2 ‐based substrate led to more efficient charge carrier generation and transport through the perovskite film …”

Multifunctional Synthesis Approach of In:CuCrO2 Nanoparticles for Hole Transport Layer in High‐Performance Perovskite Solar Cells

“…Meanwhile, there are different approaches to explore ways for further improving the electrical properties. Recently, ternary metal oxide NPs such as CuCrO 2 , CuGaO 2 , and NiCo 2 O 4 NPs have been studied for HTL in PSCs due to their advantage of bandgap tunability by changing the metal ratio and their decent conductivity. For p–i–n inverted PSC structures, there are concerns on the quality of the film formed from NPs such as the packing of NPs and the morphology of the film particularly for large size NPs such as CuGaO 2 NPs, which may influence the quality of perovskite film and increase dark current.…”

“…For p–i–n inverted PSC structures, there are concerns on the quality of the film formed from NPs such as the packing of NPs and the morphology of the film particularly for large size NPs such as CuGaO 2 NPs, which may influence the quality of perovskite film and increase dark current. CuCrO 2 NPs show a fine size of about 10 nm and can be well‐dispersed for forming well‐pack HTL film in PSCs . The common method for synthesizing CuCrO 2 NPs is the hydrothermal method and most reported process takes very long reaction time of 50–60 h at the temperature of 240 °C .…”