High Thickness Tolerance in All-Polymer-Based Organic Photovoltaics Enables Efficient and Stable In-Door Operation.

Area of Science:

• Materials Science
• Renewable Energy
• Organic Electronics

Background:

• Organic photovoltaics (OPVs) offer tunable optoelectronic properties for low-power indoor electronics.
• Thick active layers (>300 nm) are desired for high photocurrent and scalable manufacturing but typically suffer from charge recombination.

Purpose of the Study:

• To demonstrate the thickness tolerance of all-polymer-based PVs for efficient and stable indoor energy harvesting.
• To investigate the reasons behind performance variations with thickness in OPVs under indoor lighting.

Main Methods:

• Fabrication and characterization of all-polymer organic photovoltaic devices with varying photoactive layer thicknesses.
• Performance testing under indoor light conditions.
• Analysis of charge recombination and photostability.
• Drift-diffusion simulations to understand charge carrier dynamics.

Main Results:

• All-polymer PV devices exhibited excellent thickness tolerance under indoor light, with optimal performance in thicker devices (320-475 nm) achieving 34.7 µW cm⁻².
• Thick devices showed significantly improved photostability compared to thin devices.
• High thickness tolerance was attributed to suppressed space-charge effects and reduced bimolecular recombination in thicker films.

Conclusions:

• All-polymer organic photovoltaics demonstrate remarkable thickness tolerance for indoor applications, overcoming typical recombination issues.
• Suppressed space-charge effects, despite unbalanced charge carrier mobilities, are key to the stability and efficiency of thick devices.
• These findings highlight the potential of all-polymer PVs for developing robust and efficient indoor energy harvesting solutions.