# Electron volts to voltage

1. Oct 31, 2008

### vw_g60t

In semiconductors it is known that the wider the band-gap the higher the output voltage, what is the theory behind this?

2. Nov 3, 2008

### Phrak

Band gap is a voltage. "Electron volts" is a measure of energy. Nobody knows what you're asking.

3. Nov 3, 2008

### Staff: Mentor

Based on vw's one other PF post so far, I'm guessing he's asking about solar cell output. vw, is that correct? Can you tell us what references you have been reading about solar cell solid state physics?

4. Nov 5, 2008

### vw_g60t

Voltage Through a PN junction with a 1.1 ev bandgap

Hi,

I have been looking at various sources including searching the internet, bu the main textbooks i have are:

1) Markvart, T. 'Solar Electricity' 2000. Southampton
2) Goswami, Kreith, Kreider. ' Principles of Solar Energy'. 2001. Florida

I think I have the answer now, which is, based on V=E/q

as each electron has 1.6 x 10xy(-19) joules, then simply multiplying this by coulomb and by the internal p.d. of the pn junction (1.1ev in extrinsic silison) then obviously the max voltage this can produce is 1.1v restricted by the bandgap.

This leads me onto another problem:

WHEN THE CELL IS CONNECTED TO A CIRCUIT AND THERE IS A LOAD CAUSING RESISTANCE, WHICH INCREASES VOLTAGE. WHAT HAPPENS WHEN THIS VOLTAGE GOES THROUGH A PN JUNCTION OF 1.1eV??

thanks

5. Nov 12, 2008

### Enthalpy

I put my contribution in an other discussion. Hope it helps for this one as well.