Tuning perovskite morphology by polymer additive for high efficiency solar cell

Area of Science:

• Materials Science
• Renewable Energy Technologies
• Photovoltaics

Background:

• Planar heterojunction perovskite solar cells offer a promising avenue for low-cost renewable energy.
• Common device structures like FTO/TiO2/CH3NH3PbI3-xClx/spiro-OMeTAD/Au face challenges in perovskite film coverage and morphology control on TiO2.
• These limitations hinder the overall performance and scalability of perovskite solar cells.

Purpose of the Study:

• To address the issues of poor coverage and morphology control in perovskite films for solar cell applications.
• To demonstrate a facile method for enhancing perovskite solar cell performance using a polymer additive.
• To investigate the impact of poly(ethylene glycol) on perovskite crystal formation and film morphology.

Main Methods:

• Incorporation of a polymer additive, specifically poly(ethylene glycol) (PEG), into the perovskite precursor solution (CH3NH3PbI3-xClx).
• Fabrication of perovskite solar cells utilizing a 150 °C processed TiO2 nanoparticle layer.
• Characterization of perovskite film morphology using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM).

Main Results:

• A 25% increase in power conversion efficiency (PCE) was achieved, reaching 13.2%.
• The addition of 1 wt% PEG resulted in improved perovskite crystal size control and reduced aggregation.
• The polymer additive facilitated the formation of a smooth, complete perovskite film over the TiO2 layer, enhancing open-circuit voltage (Voc) and short-circuit current density (Jsc).

Conclusions:

• The use of a polymer additive in the perovskite precursor solution is an effective strategy to overcome film formation challenges.
• This low-temperature solution process (<150 °C) offers an energy-conserving alternative to traditional high-temperature sintering methods for TiO2 layers.
• The optimized 1 wt% PEG addition provides a facile and scalable route to high-efficiency perovskite solar cells.