Organic electroluminescent display (OLED) has been paid much attention because OLED has high contrast ratio, short response time, and wide viewing angle. OLED is manufactured by vacuum evaporation process or solution process. OLED manufactured by vacuum process is currently used in small display such as smart phones and cellular phones. Display makers are focusing on development of large area display such as TV at this moment. Solution process is attractive for TV because it can be manufactured for large area display with low cost. Light emitting polymer (LEP) is one of most promising material for display manufactured by solution process. In this paper, we describe development of LEP in Sumitomo-Chemical, for example, improvement of efficiency and lifetime, and show the latest materials performance from these studies.