Windows File Explorer displays the thumbnails for various supported pictures and video formats when you open a folder containing these types of files. Unfortunately, Windows does not support PSD images produced by Adobe Photoshop software. As such, File Explorer also does not display the thumbnail previews for PSD files which is a very disappointing fact. If you do not want to open the PSD files in a compatible image viewer just to look what is inside that file, then you can enable the thumbnail preview for PSD file types easily using the instructions below.
Since Windows does not support PSD images by itself, you will have to use a third party program like Pictus for adding the thumbnail preview support for these image file types. Pictus is a small image viewer program for Windows, but it also adds thumbnail preview for various file types like BMP, GIF, JPG, PCX, PNG, PSD (Adobe Photoshop), PSP (Corel Paint Shop Pro), TGA, TIFF, WBMP and XYZ.
During the installation of the Pictus software, you should choose the option Show thumbnails in Explorer. This is necessary for enabling the thumbnail previews. After this it will ask you to associate various image types with Picture, which you may deselect if you do not want Pictus to be your default image viewer.
After having installed Pictus in the aforementioned way, you should be able to see thumbnail images for PSD image types in File Explorer. In the following screenshot, it is displaying the thumbnail preview images for both JPEG and PSD file types in Windows 8.
Conclusion: Pictus is a small gem of an image viewer for Windows that is able to enable thumbnail previews for various image types that are not directly supported by Windows. You can use it to have thumbnail previews of PSD image types easily in a matter of seconds.
You can download Pictus from https://poppeman.se/pictus/.