Opto-electronic energy conversion: which device primarily converts incident light energy directly into electrical energy for power generation or sensing?

Introduction / Context:
Many electronic components respond to light, but only certain devices are intended to convert light energy directly into electrical power. Distinguishing among light-sensitive components is key for selecting parts in energy-harvesting and sensing applications.

Given Data / Assumptions:

• We want primary light-to-electric conversion.
• Direct electrical output under illumination is desired.
• Context includes both energy harvesting and sensing.

Concept / Approach:
A solar cell (photovoltaic cell) generates a voltage and current when illuminated via the photovoltaic effect. Photodiodes and phototransistors are light sensors optimized for signal detection, typically requiring bias and producing small currents; they are not intended primarily as power sources. A thermocouple converts temperature differences to voltage via the Seebeck effect, not light directly.

Step-by-Step Solution:

Verification / Alternative check:
Solar panels, which are series/parallel assemblies of solar cells, are ubiquitous proof of light-to-electric power conversion at practical scales.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming all light-sensitive devices are interchangeable; confusing photovoltaic effect (power) with photoconductive or phototransistor sensing (signal).

Final Answer:
solar cell.