Our studies converge on three central findings. First, people use emojis in text-based communication to convey emotional experience. Second, the amount and diversity of emojis causally increases happiness during social interactions. Third, across 122 countries, higher total amount and greater diversity of emoji usage per capita and per user correlate with higher national happiness. Across levels of analysis, our results suggest that both the amount and diversity of digital emotion expression influences well-being.

An academic paper looking - essentially - at emojis  :-OOO !! ;-)