Laser Derived Electron Transport Layers with Embedded p–n Heterointerfaces Enabling Planar Perovskite Solar Cells with Efficiency over 25%

Abstract

Electron transport layers (ETLs) with pronounced electron conducting capability are essential for high performance planar perovskite photovoltaics, with the great challenge being that the most widely used metal oxide ETLs unfortunately have intrinsically low carrier mobility. Herein is demonstrated that by simply addressing the carrier loss at particle boundaries of TiO2 ETLs, through embedding in ETL p–n heterointerfaces, the electron mobility of the ETLs can be boosted by three orders of magnitude. Such embedding is encouragingly favorable for both inhibiting the formation of rutile phase TiO2 in ETL, and initiating the growth of high‐quality perovskite films with less defect states. By virtue of these merits, creation of formamidinium lead iodide perovskite solar cells (PSCs) with a champion efficiency of 25.05% is achieved, setting a new benchmark for planar PSCs employing TiO2 ETLs. Unencapsulated PSCs deliver much‐improved environmental stability, i.e., more than 80% of their initial efficiency after 9000 h of air storage under RH of 40%, and over 90% of their initial efficiency at maximum power point under continuous illumination for 500 h. Further work exploring other p‐type nanocrystals for embedding warrants the proposed strategy as a universal alternative for addressing the low‐carrier mobility of metal oxide based ETLs.

Reinforcing built-in electric field to enable efficient carrier extraction for high-performance perovskite solar cells

“…14a). 90 The p-type CdTe NCs with Mie-scattering characteristics were prepared (Fig. 14b and c) in the precursor solvent used for the chemical bath deposition of the TiO 2 ETL, and then positioned at the particle boundary of the TiO 2 ETL by liquid phase pulsed laser irradiation technology.…”

Improving the Photoelectric Conversion Efficiency of Cs2TiBr6-Based Perovskite Solar Cells Using a Theoretical Simulation Method

“…The resulting P−N heterointerface not only eliminated electron trapping on the TiO 2 nanoparticles but also facilitated electron migration between neighboring TiO 2 particles. 48 Similarly, Yang et al achieved in situ fluorination of TiO 2 nanocrystals using a straightforward nonhydrolytic method. This process led to the formation of Ti−F bonds, enhancing electron mobility and reducing the density of electronic defect states.…”

Efficient Perovskite Photovoltaics by a Nanostructured Ga2O3 Hole-Blocking Layer

“…Organometallic perovskite solar cells (PSCs) have garnered considerable attention as a very promising and cost-effective photovoltaic technology, primarily because of their competitive performance when compared to silicon solar cells. − Nowadays, n-i-p PCSs have achieved a power conversion efficiency (PCE) of 26.1%. − Perovskite-based photovoltaics are categorized into many classes according to their cell structure, such as typical, planar, mesoscopic, and inverted, as well as the position of their charge-transporting layers. − Thus far, the planar structure has shown the highest verified efficiency. Hence, scientists are generally interested in both conventional (n-i-p) and inverted (p-i-n) planar PSC layouts. − Out of all of the electron transport layers (ETLs), compact and mesoporous titanium dioxide (TiO 2 ) ETLs have demonstrated high efficiency. − Nevertheless, the TiO 2 layer continues to have issues with defect trap levels and low electron mobility, which impede electron transportation and, thus, influence the charge collection capacity …”