Zach Daniel Moore, 26, covered his eyes and bowed his head on Monday as a NSW District Court sentencing judge recalled how the Rooty Hill man targeted 10 victims over 20 months.

When one victim told him she was 13 years old, Moore responded: "Oh, that sounds fun. ... I hope I can see you nude in photos."

He threatened to "show the world how dirty" a 14-year-old girl was if she didn't send him nude photos while other children were dubbed the man's "toy", "pet" or "slave" and told to refer to him as their master in text-based sexually explicit conversations.

After a tip-off from Europol, the European Union's law enforcement agency, Moore was arrested in October 2020.

He entered early guilty pleas to 10 offences including using a carriage service to solicit child abuse material.

Moore told the court in September sexual gratification was a factor but he "mainly done it for time to kill" and "was never just focusing on the chats".

The level of bullying Moore suffered in high school meant he had an extremely limited social circle, was "socially awkward" and struggled outside the home without his ill father, the court was told.

He turned to online conversations in 2016, finding he was more comfortable.

The Crown accepted the offender had a deprived background and a depressive disorder but that only slightly reduced his moral culpability for consistent requests of child abuse material.

Judge Karen Robinson accepted the 26-year-old was genuinely contrite and had "some" appreciation for the harm caused to his victims.

She found Moore's offending generally lacked sophistication, noting he'd used his own name when communicating with the children.

There was no evidence any material received by Moore was transmitted elsewhere.

But jail was the only option for such serious offending, she said.

The head sentence of three years and eight months was backdated to Moore's arrest.

He will be eligible for parole on October 20, 2022.

Australian Associated Press