Breakthrough barium titanate solar panels are 1000x more powerful than existing panels
(www.thebrighterside.news)
It says in the article
compared to pure barium titanate of a similar thickness, the current flow was up to 1,000 times stronger
And in the referenced paper
In addition, the photoresponse from SBC222 is 1000 times higher than that from BTO
Neither sound like a measure of efficiency to me. But I'm also no expert and the paper went well beyond my head.