Sony launched a series of new smartphones on Monday with super-tall screens and cinema-quality features in the hope that video creators and movie buffs can help boost its struggling mobile unit.

Sony's Xperia 10, 10 Plus and 1 smartphones come with a 21:9 aspect ratio screen, which the company said would allow users to watch videos in the same format as a movie theater. Most smartphones from companies like Apple or Samsung come with 16:9 or 18:9 aspect ratios.

A 21:9 device would allow you to watch many films without any black bars on the sides, top or bottom. However, most non-cinema content would not be readily available in the format.

The new Xperia lineup was revealed Monday at Mobile World Congress in Barcelona, Spain. The premium Xperia 1 measures 6.5 inches tall, making it one of the taller smartphones on the market.

Other key features of the Xperia 1 include:

4K HDR OLED screens.

Triple-lens camera system.

Pricing starting at £799 ($1,043)

The ultra-wide screens are Sony's latest attempt to lure in an audience consuming, producing and editing more videos on mobile phones. Last year, research firm e-Marketer estimated 78 percent of worldwide video viewing is on mobile.

Sony has struggled to keep up with competition from Apple and Samsung in the premium smartphone market, as well as Chinese players like Huawei, OnePlus and Oppo. Counterpoint Research estimates Sony's market share fell from 0.9 percent of total smartphone shipments in 2017 to 0.5 percent in 2018.

"Sony has been relegated to niche player," said Neil Shah, partner and research director at Counterpoint, in an email to CNBC.

Sony isn't the first company to use screen size ratios to try to offer higher-quality video. A growing number of device makers have fiddled with screen size and resolution to try to offer a better viewing experience.

Sony said that in addition to its Sony Pictures films, brands including Netflix, Amazon Prime Video and YouTube are increasingly providing content in 21:9. The Japanese tech giant also said it's working with the makers of "Fortnite" and other firms to offer video gaming experiences in the new format.