EFS only does data at rest encryption. Meaning while it is on your hard drive it is encrypted. If someone took your hard drive out and tried to look at the data they could not. When you access that data Windows does on the fly decryption because the key is based on your Windows SID. If you copy the encrypted files to your android device or any other storage media Windows does the same thing. On the fly decryption and then copies the data. Even many full disk encryption solutions won't keep the data encrypted if you copy it unless you go with a enterprise product such as Checkpoint Encryption or Sophos Encryption which can be configured with a policy to prevent copying to storage media without encrypting the media. You could , like a said, use True Crypt or Vera Crypt to create encrypted containers and put your data in them. If those containers get copied they stay encrypted.