I don't think it is possible to grow a thin film of Pentacene as single crystal. You can however grow larger size single crystals (mm - cm range) of Pentacene using OVPD technique

Thank you Dear Salahud Din, Now a days people are doing research in nanometer scale, I need in nano meter range. If you know any other process let me know.

Yes , Using horizontal physical vapor transport method or Liquid-Phase Crystallization Process

Ref:

http://dx.doi.org/10.1016/S1369-7021(07)70016-0

http://dx.doi.org/10.1063/1.1631736

Dear Ajay, I was under the impression that you wanted to fabricate an entire thin film of pentacene as single crystal on larger size. When you say nano meter range - those are referred to as nano structures. Anyways If you can tell me more about your process and your requirements and for what application, I may be able to help you further.

Thank you Dear Logesh Karunakaran, I will contact you soon

Dear Salahud Din, I would like fabricate the Single crystal Field effect transistor in nano range. Please tell me the process