The vertical organic space-charge-limited transistor made of P3HT and small-molecule phosphorescent organic light-emitting diode (OLED) are made on two separate glass substrate by blade coating, then soldered vertically together by tin balls with 40μm diameter. The soldering is done by hot wind of 150°C for 5min Contact resistance is only 10Ω. The vertical transistor is annealed at 150°C for 5min before soldering to enhance the output current up to 25mA/cm2 and give high thermal stability. Both OLED and the annealed vertical transistor are not affected by the soldering process. The vertical transistor has 1/4 of the OLED area and turns on the bottom-emission white OLED up to 300cd/m2 and orange OLED up to 600cd/m2. The entire operation is within 8V. OLED and transistor array can therefore be made on separate glass substrates then soldered together to form the display.