Composition and Energy Band–Modified Commercial FTO Substrate for In Situ Formed Highly Efficient Electron Transport Layer in Planar Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have received much attention and with them a power conversion efficiency (PCE) of over 22% has been achieved. Electron transport layers (ETLs) based on metal oxide materials play an important role in transferring electrons and reducing back recombination. However, existing fabrication approaches are generally waste too many materials and consume too much energy for commercial application. Here, a brand new plasma preannealing procedure is proposed that can replace the traditional ETL preparation process and alleviate the above-mentioned problems. A pure SnO 2 phase in situ formed on the fluorine-doped tin oxide (FTO) surface can be obtained at room temperature by only 15 min oxygen plasma assisted reaction without postheating treatment. It enables the precise control of compositions, defects, and energy levels of band at the surface of FTO substrate, resulting in a prominent PCE of 20.39% with excellent stability and reproducibility. This simple and efficient source-free fabrication technology provides a versatile platform for the manufacture of PSCs in the future.

In Situ Formed Gradient Bandgap‐Tunable Perovskite for Ultrahigh‐Speed Color/Spectrum‐Sensitive Photodetectors via Electron‐Donor Control

“…Corresponding Mott‐Schottky curves are shown in Figure 3c,d, respectively. The built‐in voltage ( V bi ), doping density ( N d ) and depletion width ( w ) were calculated31,33 and summarized in Table S2 (Supporting Information). The V bi at the interface of HTM/perovskite decreases gradually while the V bi at the interface of ETM/perovskite behaves on the contrary.…”

Realizing Stable Artificial Photon Energy Harvesting Based on Perovskite Solar Cells for Diverse Applications

“…The spectral mismatch brings about an energy loss and increased recombination rate 15,16. As a result, previously reported devices that convert such artificial light have a deficient open‐circuit voltage ( V oc ) less than 0.9 V. Up to now, the further improvement of efficiency mainly depends on interfacial modification strategy, and thus little progress has been made 17–21. Only few pioneer research was major in the absorber aimed for the dim light 22,23.…”

“…[15,16] As a result, previously reported devices that convert such artificial light have a deficient open-circuit voltage (V oc ) less than 0.9 V. Up to now, the further improvement of efficiency mainly depends on interfacial modification strategy, and thus little progress has been made. [17][18][19][20][21] Only few pioneer research was major in the absorber aimed for the dim light. [22,23] To bridge the large gap between the application of perovskite solar cells in daily life and under simulated sun light, three challenging issues should be resolved: i) Preparing bandgap-adjustable perovskite films with uniform and smooth surface and high crystallinity, together with the capability of…”

Graded Bandgap Perovskite with Intrinsic n–p Homojunction Expands Photon Harvesting Range and Enables All Transport Layer‐Free Perovskite Solar Cells

“…It should be mentioned that the existence of ETL contributes little to the PCE improvement for graded Pb/Sn perovskite‐based device. It may be due to the fact that the FTO substrate with the fluorine‐doped tin oxide can extract electrons by itself . The back recombination is suppressed by the perovskite n‐type area.…”

“…It may be due to the fact that the FTO substrate with the fluorine-doped tin oxide can extract electrons by itself. [21] The back recombination is suppressed by the perovskite n-type area. It may be the same reason that Pb perovskitebased PSCs with ETL-free structure also show a decent PCE of 16.8%.…”