Massachusetts design solar conversion efficiency roadmap

Since the concept of "artificial leaves", the scientists have been high hopes for it, hoping it will eventually bring a cheap self-control system to provide electricity for the billions of people in developing countries. According to physicist organizational networks reported recently, the Massachusetts Institute of Technology (MIT), a research group of the limiting factor in the efficiency of the system by the "artificial leaves" a detailed analysis and re-design, and bring it closer to reality, and is expected to bring a kinds of practical, inexpensive commercial prototype. Related papers published in the National Scientific Research Journal.

"Artificial leaves" system combines two techniques: First, the standard silicon solar cell, the wind turbine inverter energy into electricity; battery is connected on both sides of the chemical catalyst. Combination of the two become the electrochemical device using photocurrent to split water into hydrogen and oxygen, hydrogen gas generated can be used for power generation by the fuel cell or other device. In this system, the photovoltaic system and the electrochemical performance of the system are determined, and therefore the efficiency of the two together can predict.

In the paper, the researchers describe their design a framework to guide the people how the power output of the solar cell and electrochemical reaction system more effectively, and more economical use of existing solar cell technology (such as silicon or telluride The cadmium) program, and identified some efficiency limit. "This is a fairly comprehensive analysis of surveys already on the market can do the best technology." MIT postdoctoral Mark? Winkler said.

The research team had in 2011 for the first time to show their "artificial leaves", but less than 4.7% of the conversion efficiency. The new study is a continuation of the original "conceptual argument. MIT associate professor of mechanical engineering Tonio? Bona Francis said that according to the latest analysis, the use of crystalline silicon band gap semiconductor, such as single, combined cobalt, nickel-based oxidation catalyst, and the maximum conversion efficiency may reach 16% or higher.

"We are very surprised." Winkler said, the traditional view is that the characteristics of the silicon wind inverter has severely limited the decomposition of water efficiency, but that is not the case. The key to improve solar energy - fuel conversion efficiency is suitable battery with a suitable catalyst, which requires a roadmap to guide how people paired in order to achieve optimal. The Bona Francis said framework they designed to simulate, in a conventional silicon cell-based system, the maximum efficiency value of approximately 16%; GaAs cell systems, efficiency limit can reach 18%.

One of the authors of the paper, the former MIT graduate student Cassandra? Cox said: "The significance of the paper is that it describes all of these technologies, and these technologies combined effect It also pointed out that the all have to face the challenge, researchers can experiment separate analysis of these negative factors. "

Such standard silicon solar charge controller generates a voltage of approximately 0.7 volts, while the hydrolysis reaction requires a voltage of 1.2 volts or more. One of the solutions to multiple cells in series. Although the the battery interface will lose energy, but also regarded as a promising research directions. Another disadvantage is that the water itself, the electrons must pass through the entire circuit, this will produce a resistance, a way to improve efficiency of the method is to reduce solution resistance, which can be realized through some tips to reduce reaction, for example, with the interposer on both sides of the distance.