White light emission from blue InGaN LED with fluorescent conjugated polymer blends

Abstract

White LEDs were fabricated by precoating blue InGaN LEDs with blends of a green emitting polymer (Poly[{9, 9-dioctyl-2, 7-divinylenefluorenylene)-alto-co- (2-methoxy-5-(2-ethylhexyloxy)-l, 4-phenylene)], PFPV) and a red emitting polymer (Poly[l-methoxy-4-(2-ethylhexyloxy-2, 5-phenylenevinylene)], MEH-PPV), which acted as the phosphor. The two polymers were blended in different weight ratios, which were found to affect the green (555 nm) and red (610 nm) emission intensity. The CIE-1931 coordinate, Tc and Ra all changed as the MEH-PPV content increased. The white LED of the polymer blend phosphor containing 33wt% MEH-PPV had a luminous efficiency of 54.2 lm/W at 20 mA with a CIE-1931 coordinate, Tc and Ra of (0.3328. 0.3547L 5488 and 71.4. respectively. © 2009 The Society of Polymer Science.