Solution‐Processed Metal Oxide Nanocrystals as Carrier Transport Layers in Organic and Perovskite Solar Cells

Abstract

There has been rapid progress in solution-processed organic solar cells (OSCs) and perovskite solar cells (PVSCs) toward low-cost and highthroughput photovoltaic technology. Carrier (electron and hole) transport layers (CTLs) play a critical role in boosting their efficiency and long-time stability. Solution-processed metal oxide nanocrystals (SMONCs) as a promising CTL candidate, featuring robust process conditions, low-cost, tunable optoelectronic properties, and intrinsic stability, offer unique advantages for realizing cost-effective, high-performance, large-area, and mechanically flexible photovoltaic devices. In this review, the recent development of SMONC-based CTLs in OSCs and PVSCs is summarized. This paper starts with the discussion of synthesis approaches of SMONCs. Then, a broad range of SMONC-based CTLs, including hole transport layers and electron transport layers, are reviewed, in which an emphasis is placed on the improvement of the efficiency and device stability. Finally, for the better understanding of the challenges and opportunities on SMONC-based CTLs, several strategies and perspectives are outlined.

Synthesis and Characterization of Spinel Cobaltite (Co3O4) Thin Films for Function as Hole Transport Materials in Organometallic Halide Perovskite Solar Cells

“…The band position levels versus RHE can be converted into the standard vacuum energy potential by approximately assuming that E RHE ≈ − E Vacuum – 0.45. , Thus, we obtained the band positions of our synthesized Co 3 O 4 with respect to the vacuum energy level, as depicted in Figure d. Compared with the band position values of the wide bandgap MAPbI 3 as well as the low bandgap MASnI 3 from the literature, we find that our synthesized p-type Co 3 O 4 has suitable band positions for function as a hole transport material to extract and transport the hole carriers from organometallic perovskites in solar cells …”

Efficient Gradient Potential Top Electron Transport Structures Achieved by Combining an Oxide Family for Inverted Perovskite Solar Cells with High Efficiency and Stability

“…Meanwhile, the transmission electron microscopy (TEM) and selected area electron diffraction characterization were conducted, and the results are shown in Figure b, the Sn-doped In 2 O 3 NPs synthesized by our low-temperature strategy show a high crystallinity and small size distribution. The average size of Sn:In 2 O 3 NPs is about 10 nm, as shown in Figure c, which is beneficial to form high-quality top ETLs with good physical contact on the perovskite surface, thereby efficiently promoting charge collection in PSCs. , Remarkably, through simple room-temperature spin-coating methods, compact and uniform Sn:In 2 O 3 and In 2 O 3 films are formed on the perovskite surface, as confirmed from the top-view scanning electron microscopy (SEM) image of the structure indium tin oxide (ITO)/hole transport layer (HTL)/perovskite/Sn:In 2 O 3 in Figure S1. Consequently, In 2 O 3 and Sn:In 2 O 3 NPs are successfully synthesized and both of them can form high-quality oxide films on perovskite films by a simple room-temperature solution approach.…”

Inorganic top electron transport layer for high performance inverted perovskite solar cells

“…As the same as ZnO, the properties of TiOx can be adjusted by doping. 204 As shown in Figure 6A, Nb doped TiO 2 boosted higher PCE and reduced hysteresis. 158 Additional electron in Nb 5+ compared with Ti 4+ enabled higher electron mobility.…”