Extremely Low-Cost and Green Cellulose Passivating Perovskites for Stable and High-Performance Solar Cells

Abstract

The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.

Interface Engineering of Air‐Stable n‐Doping Fullerene‐Modified TiO2 Electron Transport Layer for Highly Efficient and Stable Perovskite Solar Cells

“…Since the first report in 2009, organometal halide perovskites have been attracting much attention owing to their large absorption coefficient, high carrier mobility, and tunable bandgap . With continuous efforts in perovskite compositions, fabrication processes and device configurations, the certified power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached an astonishing record of 25.2% . Generally, a planar PSC device is composed of a perovskite layer as light absorber sandwiched between electron and hole selective contacts.…”

Defect passivation by nontoxic biomaterial yields 21% efficiency perovskite solar cells

“…The calculated electron trap density decreases from 2.35 Â 10 16 (pristine) to 1.80 Â 10 16 cm À3 (with betulin). The electron mobility (m e ) is determined in the SCLC regime by the Mott-Gurney law [61]:…”

Nanocellulose‐based polymer composites for energy applications—A review

“…Recently, Yang et al . fabricated perovskite films with an enlarged grain size and decreased defect density by introducing a low cost green polymer, ethyl cellulose into the layer . The resulting device has shown the PCE to 19.27% and hysteresis index decreased by three times.…”

“…A comparison on the basis of stability of bare perovskite solar cells with and without Ethyl Cellulose. Reproduced with permission . [Color figure can be viewed at wileyonlinelibrary.com]…”