Dear Manish Meena

For high radiation you can use low band-gap energy solar cells, like CIGS solar cells (Eg = 1.01 to 1.5 eV) CdTe, CZTS, mc-Si .....

Good luck.

You might have to use multijunction cells, but they are quite expensive.

That is such a broad range, I mean the solar spectrum is about that wide you might as well ask what's the best solar cell under sunlight. The best is III-V multijunction, the most cost-effective is probably silicon.