The Nokia 6 features a hybrid In-Cell touch display which allows smartphones to have a slimmer form factor and less weight, because the touch input and the screen are integrated into a single layer, and it's said that this technology even improved the resolution, but the main purpose of this In-Cell technology is to allow lighter and thinner phones. This technology is used since 2012 and now used in almost all high-end smartphone displays. There is also a competitive technology called on-cell, so compared to in-cell where the conductive layer is above the same layer of the TFTs, whether with on-cell, the multitouch functionality is embedded on top of the thin-film transistor. Samsung AMOLED displays only allow On-Cell solution to be used with their screen technology while other plans support the in-cell technology as well.
According to data statistics about touch displays specs for 2015-2016 published by WitsView on September 2015, in 2015, On-cell and In-cell displays grabbed 40.6% of the touch displays (other were Single Glass, Double Glass, Metal Mesh/SNAW and ITO Film technologies), whether in 2016, there is a rise in the trend for On-cell and In-cell, jumping to 47.8%, grabbing market share from all the other technologies. The main reason for that is that those technologies found themselves also in mid-range devices as well, not just in high-end devices, and this trend will continue through 2017 and beyond.
Now regarding the Hybrid version of the In-cell panel technology, the one used in the Nokia 6. While In-cell can be used for LCD and AMOLED, On-Cell supports LCD, AMOLED and e-paper display, the Hybrid in-cell supports only LCD displays (source). In Hybrid In-cell the transmitting layer of the touch sensor is in-cell over the TFT glass, while the receiving layer is On-Cell and resides on the color filter glass top layer, just below the polarizer and the cover glass layers. Because this technology utilizes both On-cell and In-cell technologies, it's dubbed Hybrid In-cell. There is also a need for a second FPC digitizer connector with the Hybrid in-cell design.
The end results in a touch display with narrower borders, thinner form factor, they are less prone to failure and are also 10% brighter or they can provide the same brightness but with less backlight, therefore helping in improving the battery life for its devices compared to discrete touch panels. By the way, the Nokia 6 display has a pick 450 nits brightness. This is not as high as the iPhone 7 (705 nits), Samsung Galaxy Note7 (1000 nits), Samsung Galaxy S7 (855 nits), so it's not the brightest out there. I'm also not sure if that number refers to the peak brightness. If you know this, please comment below. From what I understand, it is the maximum brightness, so it's suppose to provide around the same brightness as the Samsung Galaxy S6 that was tested by displatemate.com and show max luminance of up to 432 nits.
According to a research published by DisplaySearch on October 2014, in 2014, the estimates still shown that there were more smartphone with discrete panels compared to integrated touch displays and in 2015 those integrated touch displays have passed the discrete ones and this trend continues to grow each year. The use of these new technologies also reduces the screen manufacturing costs for manufacturers and reduces cost for phone manufacturers which now can buy touch and display from a single source vendor (source).
The Hybrid In-cell technology is therefore relatively new. For example, in October 13, 2016, Synaptics announced it's first Hybrid In-Cell TDDI (Touch Display Driver Integration) technology aiming it t to the smartphone market with panels ranging from HD to WQHD resolution (source) and offering the best in class touch capacitive sensing performance.
So you can see that there is a benefit for the Nokia 6 utilizing this screen technology, and I believe this is one reason why HMD could lower the cost of the phone and why it mentioend it in the press release ("..has a bright hybrid in-cell 5.5-inch screen with full HD resolution.." - hmdglobal.com). This technology allows Nokia to create a slimmer phone with a brighter and high-performing touch screen that is usually reserved for high-end smartphone.
If you have anything to add, please comment below. I'm interested to hear your own opinion on this technology.