Ch.12 - Solids and Solid-State Materials

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.12 - Solids and Solid-State Materials

Problem 94

Chapter 12, Problem 94

What are the main differences between an LED and a photovoltaic cell?

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LEDs (Light Emitting Diodes) and photovoltaic cells are both semiconductor devices, but they operate in opposite ways.

An LED converts electrical energy into light energy. When a voltage is applied, electrons recombine with holes in the semiconductor material, releasing energy in the form of photons (light).

A photovoltaic cell, on the other hand, converts light energy into electrical energy. When light photons strike the semiconductor material, they excite electrons, creating electron-hole pairs that generate a current.

LEDs are used in applications where light emission is needed, such as in displays and lighting, while photovoltaic cells are used in solar panels to generate electricity from sunlight.

In summary, LEDs emit light when powered by electricity, whereas photovoltaic cells generate electricity when exposed to light.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

LED (Light Emitting Diode)

An LED is a semiconductor device that emits light when an electric current passes through it. The light is produced by electroluminescence, where electrons recombine with holes in the semiconductor material, releasing energy in the form of photons. LEDs are commonly used for lighting and display purposes due to their efficiency and long lifespan.

Photovoltaic Cell

A photovoltaic cell, or solar cell, converts light energy directly into electrical energy through the photovoltaic effect. When photons from sunlight strike the cell, they excite electrons, creating electron-hole pairs that generate a flow of electricity. Photovoltaic cells are primarily used in solar panels for renewable energy generation.

Energy Conversion Mechanisms

The key difference between LEDs and photovoltaic cells lies in their energy conversion mechanisms. LEDs convert electrical energy into light energy, while photovoltaic cells convert light energy into electrical energy. This fundamental distinction defines their applications: LEDs for illumination and displays, and photovoltaic cells for harnessing solar energy.

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Conversion Factors

Related Practice

Textbook Question

A photovoltaic cell contains a p–n junction that that converts solar light to electricity. An optimum semiconductor would have its band-gap energy matched to the wavelength of maximum solar intensity at the Earth's surface. (a) What is the color and approximate wavelength of maximum solar intensity at the Earth's surface? Refer to the figure for Problem 12.102.

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Textbook Question

Arrange the following materials in order of increasing electrical conductivity. (a) Cu (b) Al2O3 (c) Fe (d) Pure Ge (e) Ge doped with In

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Textbook Question

Classify the following semiconductors as n-type or p-type. (a) Si doped with In (b) Ge doped with Sb (c) Gray Sn doped with As

Textbook Question

Considering only electronegativity, rank the LED semiconductors made of solid solutions in order of increasing bandgap energy. Al0.40Ga0.60As, Al0.25Ga0.75As, Al0.05Ga0.95As

Textbook Question

A photovoltaic cell contains a p–n junction that converts solar light to electricity. (a) Silicon semiconductors with a band-gap energy of 107 kJ/mol are commonly used to make photovoltaic cells. Calculate the wavelength that corresponds to the band-gap energy in silicon.

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Textbook Question

Write a balanced equation for the synthesis of the 2–6 semiconductor ZnTe by chemical vapor deposition from dimethylzinc, Zn(CH₃)₂, and diethyltellurium, Te(CH₂CH₃)₂, assuming that the other product is gaseous propane (CH₃CH₂CH₃).