Silicon photovoltaics are a proven sustainable energy solution and take up 90% of the solar cell market. Silicon cells have many practical advantages associated with them, including high cell efficiency, stability and longevity. They are also extremely cost effective. The cost of mass produced silicon cells has dropped below $1/W, in some cases as low as $0.3/W. At the same time, efficiency continues to increase to 20%. The biggest hindrance to further increases in efficiency are high rates of recombination at the surface of the cells, which is what Shinde et. al (2016) have been working on.
In order to lower the rates of recombination, the technique of passivation has been employed. SiNx and SiO2 compounds have been used for passivation in the past. Although the desired surface passivation is accomplished, these compounds require high process temperatures (300° – 1000° C). At these temperatures, the properties of the silicon crystalline structure are affected. If these temperatures are reduced, efficiency and longevity are expected to increase.
To combat high process temperatures, new techniques have been presented. It has been shown that passivation can be achieved by using Si-O and Si-H and organic passivation. Shinde et. al (2016), look at passivation of n-type emitter by organic cover layer Oleylamine (OLA). This passivation technique will increase efficiency and has the ability to be processed at room temperature. Continue reading →
An MIT research team has recently developed what is believed to be the thinnest, most lightweight, and flexible photovoltaic cell, with the ability to be installed onto any surface and the potential to charge any portable electronic device. The solar cell is so light that it is able to rest on a soap bubble without the bubble being popped. The real key to this innovation Is a one-process approach in manufacturing the ultra-thin solar cell and the unique substrate that supports it. Continue reading →
In 2011, Daniel Nocera engineered an artificial leaf that uses only sun and water to produce energy (Chandler, Sep 30, 2011). The leaf was made of silicon solar plates with different catalytic materials bonded on each side (Chandler, Sep 30, 2011). When the plate is placed in water and exposed to sunlight, one side produces hydrogen bubbles, and one side oxygen bubbles, which can be stored and used for energy (Chandler, Sep 30, 2011). Although this was an important innovation in renewable energy, major shortcomings of the invention was that it produced hydrogen, which does not easily fit into our existing energy infrastructure, rather than liquid fuel. Recently, Nocera has collaborated with biologists at Harvard University to engineer bacteria that convert hydrogen into an alcohol-based fuel (Nunez, Feb 9, 2015). Continue reading →
While fossil fuels will continue to meet the vast majority of the planets energy needs for the foreseeable future, renewable energy is the fastest growing source of electrical power in the world, increasing at a rate of 2.8 percent annually.[i] With the effects of green house gas emissions becoming more apparent on the planet, renewables will become more and more important in global energy generation. Solar energy is one of the most affordable, cleanest, and most secure of the renewables, and is at the forefront of renewable power. This post will give a brief analysis of the different types of solar power and their prospects for the future. Continue reading →
The looming problem with renewable energy—especially in California where there is potential for a great deal of solar energy—is finding the right balance between attractive new, but intermittent, solar and wind power plants, and some other source of generation large enough that dispatching it will meet any energy demand, even if the wind isn’t blowing and the sun isn’t shining. A new paper by Abebe Solomon, Dan Kammen, and Duncan Callaway, researchers in the Energy & Resources Group at the University of California Berkeley, calculates that if energy dumping doesn’t occur, the best we can hope for in California without energy storage, is meeting 29% of our energy needs with solar and Continue reading →
Bernardi et al. (2013) investigated the absorbance of graphene and three different monolayer transition metal dichalcogenides (TMDs)—MoS2, MoSe2, and WS2—alone and in various combinations as the active layer in ultrathin photovoltaic (PV) devices. In calculating the upper limits of the electrical current density (measured in mA/cm2), each material can contribute to the total absorption of a device. The authors found that subnanometer thick graphene and TMD monolayers can absorb the equivalent short-circuit currents of 2–4.25 mA/cm2, while 1 nm thick Si, GaAs, and P3HT (commonly used materials in current PV devices) were found to generate currents between 0.1–0.3 mA/cm2. Further testing suggested that the high absorption of the monolayer MoS2 is due Continue reading →