Organic Solar Cells

The efficiency of any mechanical or electrical or even political system is a measure of how well the system performs its function. The efficiency of a solar panel is a measure of the amount of incident sunlight that is converted into electricity. In other words, a solar panel module rated 25% efficient only converts 25% of the total sunlight that falls on its surface into usable electricity.


A major determinant of efficiency is the type of material and technology used in making the solar cells. Advances in solar technology has seen a continuous rise in efficiency ratings of mass-marketed solar panels from just 12% to almost 24%.


Much of the solar industry research and development effort revolves around developing more efficient solar cells. The necessity of developing more efficient solar cells is decided by the need to harvest more electricity from the solar cells per installation space. Supported by new technologies, sustained research and development efforts, effective business models, innovative policies and access to capital, the solar industry is a dynamic one that continues to push back on existing limitations.

Source: Advanced Science News

How OSCs Change the Game

The first organic solar cell was developed in 1958. But organic solar cell (OSC) or organic photovoltaic cell (OPV) or polymer solar cell (PSC) technology had to wait till the 2000s with improvements that emerged from the field of organic light-emitting diodes, to see a significant rise in efficiency.


Learn how solar panels are manufactured here.

1. They Are Lightweight and Flexible

Conventional solar panels are rigid and have to be 'installed'. Typically, solar cells are made from silicon. In an 'organic' or 'plastic' or 'polymer' solar cell, instead of silicon, carbon-based materials are used.


Since they are plastics that can be dissolved in solvents and made available in liquid form, OSCs can be easily 'printed' onto any surfaces that are inaccessible to regular solar panels. They are also ultra-thin and can be a thousand times thinner than traditional solar cells. They make possible a wide range of applications possible. For instance, they can be used in the making of 'solar fabrics', that is dresses fitted with solar cells and generating light on the go. They can also be used in far more versatile ways and can be integrated into objects like backpacks, canopies, windows, desks, walls, etc.


2. They Can Be Made to Be Transparent, Semi-Transparent and Coloured

Typically, like most plastics, they can be made to be transparent, semi-transparent and in variants of colours. In this way, they can be integrated into windows. and in the making of solar cars.

Source: Toyobo.com
3. Lower Shipping Costs

A much larger quantity can be transported per time meaning that they can reach developing countries faster and easier without any spike in net costs.


4. Less Energy-Intensive Manufacturing Process

Like most plastic products, their manufacturing process requires less energy. This has the potential of making them cheaper than panels manufactured in the conventional methods of heating silicon at very high temperatures. In the meantime, however, its production costs bothering mainly on the costs of raw materials, are much higher than the conventional methods because it is still a nascent and small industry.


Drawbacks

1. They Do Not Last Long Enough

In comparison to crystalline solar cells, OCS generally have a low life-cycle due to incorporating organic parts that are adversely affected by environmental conditions. To give them a longer life, they have to be encapsulated under glass surfaces like conventional solar cells. This will lead to the loss of their greatest characteristics, flexibility.

A Module of Six Organic Solar Cells. Source: FRAUNHOFER ISE/BERND LAMMEL
2. They Are Being Crushed By The Competition

Another new type of solar cell technology, the perovskite solar cell in the wake of its emergence has received the most attention from major industry stakeholders and organizations that provide research funding. In China nonetheless, research and development in OSC technology continues to grow steadily as the next frontier.


3. Still Low Efficiencies

As of now, OSCs have achieved efficiencies near just 11%. This, in addition to their low life-cycle makes them still largely unattractive. In September 2021, researchers from North Carolina State University and Tianjin University and Zhejiang University in China demonstrated a OSC that could reach the 15% mark in efficiency. Regardless of the efforts, in comparison, this is still rather low.

A Researcher at the University of Michigan Holds an OCS. Source: LaserFocusWorld.com
4. Not So Easy to Commercialize

In March 2020, Japanese fabric makers, Toyobo and a French public research organisation, CEA, announced that they had succeeded in making OSCs with the world's top-level conversion rates in a dim room. Toyobo say they will look to use the material by March 2023 as a wireless power source for temperature-humidity and motion sensors. But only just that.


The path to commercialization is still ahead. Considering the promise OSCs holds for the solar industry, this path is not very far ahead. Research on OSCs continues to focus on increasing their efficiency and life-cycle. Their short life-cycle does not make them a dead end. Researchers found that removing a molecule from the topmost layer of the cells, blocking out UV rays from reaching the cells and adding a sunscreen to the sun-facing side of the glass, can potentially reduce damages caused by atmospheric oxygen, sunlight and water. And by so doing increase the lifetime to up to 30 years!


This technology has the theoretical potential to provide electricity at a lower cost than the traditional solar cell technologies. Hence, the solar sector's continuous interest in optimizing the technology.

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