TiO₂ Phase Junction Electron Transport Layer Boosts Efficiency of Planar Perovskite Solar Cells

Abstract

In the planar perovskite solar cells (PSCs), the electron transport layer (ETL) plays a critical role in electron extraction and transport. Widely utilized TiO2 ETLs suffer from the low conductivity and high surface defect density. To address these problems, for the first time, two types of ETLs based on TiO2 phase junction are designed and fabricated distributed in the opposite space, namely anatase/rutile and rutile/anatase. The champion efficiency of PSCs based on phase junction ETL is over 15%, which is much higher than that of cells with single anatase (9.8%) and rutile (11.8%) TiO2 as ETL. The phase junction based PSCs also demonstrated obviously reduced hysteresis. The enhanced performance is discussed and mainly ascribed to the excellent capability of carrier extraction, defect passivation, and reduced recombination at the ETL/perovskite interface. This work opens a new phase junction ETL strategy toward interfacial energy band manipulation for improved PSC performance.

Dopant‐Free, Amorphous–Crystalline Heterophase SnO2Electron Transport Bilayer Enables >20% Efficiency in Triple‐Cation Perovskite Solar Cells

“…Numerous research outcomes have demonstrated that the energy band alignment and interfacial charge recombination between the ETL and perovskite layer exert a significant impact on the device performance. [ 4–7 ] Therefore, it is pre‐requisite to develop an ETL with tailored morphology, optoelectronic properties, and compatible band alignment with perovskite, in order to fabricate high performance PSCs.…”

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

“…To find the influences of the perovskite and ETL on the charge dynamics in the perovskite solar cells, electrochemical impedance spectroscopy (EIS) was measured, and the results are summarized in Figure S16 (Supporting Information). All EIS curves contain two circular arcs, which can be fitted as the charge transport resistance ( R ct ) at the high‐frequency region and the charge recombination resistance ( R rec ) at the low‐frequency region 42–44. All fitted parameters are summarized in Table S4 (Supporting Information).…”

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

“…We can fit the charge transport resistance ( R ct ) of P‐FTO/perovskite interface from the high‐frequency circular arcs which reflects the carrier extraction ability of ETL. The carrier recombination resistance ( R rec ) can be extracted from the low‐frequency circular arcs which is inversely proportional to interface recombination . The series resistance ( R s ), R rec , and R ct are shown in the inset table.…”