Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
photoelectrically is an adverb meaning "by photoelectric means". It carries one recorded sense.
by photoelectric means
“they measured it photoelectrically”
Definitions, synonyms and semantic relations for photoelectrically come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.