There are two ways to prevent implantation:

The "Morning after Pill"
Tetragynon: The medication is taken within 48 hours of unprotected intercourse;  it can reduce the risk of pregnancy from 75 to 89 % if the condom breaks, your diaphragm or your cervical cap becomes dislodged. Can only be prescribed by a physician. It is a regular estrogen/progesterone birth control pill ( Neogynon,
Stediril d = 50 µg ethinylestradiol + 250 mg levonorgestrel). In emergency cases (you don't can find any physicians) you can take each other 28-pill birth control pack (only combined pills with 50 µg estrogen and a progesterone), use any of the first 21 pills for emergency contraception.
Take two pills immediately (in the pharmacy), swallow the second dose (the other or next two pills) 12 hours after taking the first dose.
Advantages: Low cost; very rare side effects.
Disadvantages: The pills will not prevent an already occurred pregnancy from continuing; frequent use of ECPs may cause periods to become irregular and unpredictable.
Effectiveness: Moderate
Cost: € 7,75 (four pills Tetragynon)

The Copper IUD

A physician can insert an IUD (Copper IUD , not Progesterone IUD ) for emergency contraception within seven days of unprotected intercourse. A later insertion is also possible to retry to prevent an abortion. You may need to rest afterwards.
Advantages : It can be left in place for very effective contraception. Or the IUD can be removed after your next menstrual period, when it is certain that you are not pregnant.
Disadvantages : Some contraindications.
Effectiveness: Better than the pills.
Cost: about € 200,-