There are still months to go for The Big Bang Theory season 11 premiere on 25 September, but co-creator Chuck Lorre has shared some details about Leonard and Penny's relationship and about struggles of keeping the show fresh and alive.

Speaking to TshisaLIVE, Lorre dished on those Leonard and Penny's split rumours and revealed that they are not headed for a divorce just yet. He said, "Not at the moment, no. It's very clear that they are very very different people. Their backgrounds, their view of life... they're extremely different so their relationship is fraught with difficulties in that they see the world very differently."

"As writers, we believe they love each other dearly, but their difficulties in their relationship, I think will continue," Lorre added.

The co-creator also spoke about Sheldon, Leonard and Howard and revealed that they are in "transition." He told the outlet, "A character like Sheldon, for instance, is very self-assured and determined about his own likeness and his thinking being correct. I think it's part of the comedy that the character must carry. He often learns that he in fact wrong. His understanding of situations is not correct."

"Leonard is interesting as well because that's a character that is filled with self-doubt, despite how intelligent he is. He is filled with self-doubt on how to proceed with relationships. Wolowitz (Howard) has always been filled with a little bit of arrogance and certainty but I think marriage and fatherhood is changing that for him. All of these characters are very much in transition. They are not set in their ways," he added of the show's lead characters.

When asked if there a sense of pressure to be the number one show with each new season, the 64-year-old American television writer said, "Obviously, it gets harder the longer we do it because over a great deal of time someone will think of a good story and the answer is 'it is good because we did it 7 years ago.' It becomes a little harder to find new material and we are pretty determined not to repeat ourselves and to keep the show fresh and alive."

Season 11 of the hit CBS comedy returns on 25 September at 8pm EST.