Breakthrough organic solar cell with 100% charge collection efficiency could revolutionize solar tech

In a groundbreaking discovery, a research team at the University of Cambridge has found that a special organic semiconductor molecule can generate electricity using a mechanism previously thought to be exclusive to inorganic materials. The work — published in the journal Nature Materials — could have a huge impact on the future of solar energy and electronics by enabling the development of single-material solar cells.

The research — a collaboration between the physics team of Professor Sir Richard Friend and the chemistry team of Professor Hugo Bronstein — focused on an organic molecule called P3TTM. The joint team discovered that when P3TTM molecules packed closely together, the unique interactions between the unpaired electrons allowed for the conversion of a photon into a usable electric charge.

In most organic materials, electrons are paired up and don't interact with their neighbors. But in our system, when the molecules pack together, the interaction between the unpaired electrons on neighboring sites encourages them to align themselves alternately up and down… Upon absorbing light, one of these electrons hops onto its nearest neighbor, creating positive and negative charges that can be extracted to give a photocurrent. — Biwen Li, lead researcher at the Cavendish Laboratory.

This represents a major shift from conventional solar cells, which require an interface between two materials — an electron donor and an acceptor — to generate electricity, a setup that limits the overall efficiency of the cells.

The material pulled its weight in lab tests, showing a quantum yield for charge generation of up to 40% in one configuration. In another configuration using a simple solar cell made from a pure film of the material, the researchers measured a near-perfect charge collection efficiency close to 100%. However, the team did not report on the overall power conversion efficiency of the configurations.

This breakthrough could foster the development of compact, highly efficient, and low-cost solar cells that use a single material instead of two. If successfully integrated, this technology could power the next generation of self-charging electronic devices.