荧光粉的内部量子效率测量

一些白色LED由两种类型的材料组成：一种是在近紫外线区域发射蓝光的发光二极管，另一种是从吸收区向近紫外线区域发出可见光的磷光体。确定磷光体的内部量子效率是评估白色LED发射效率的一个重要参数。分子发出荧光的效率由其量子产率来描述，内部量子效率定义为样品发射的光子数量与样品吸收的光子数量的比率。Application NoteFP-0017 Internal Quantum Efficiency Measurement of2/3Application NotePhosphor Powders Internal Quantum Efficiency Measurement o f Phosphor Powder s Some white LEDs cons i st of two types of materials： a l umi n escent diode that emits a blue lig h t i n the n ear-UV region， and a phosphor that em i ts visible light f r om the absorpt i on to the near-UV r egio n . Dete r mi n ing a phosphor's inter n al quantum efficiency i s an important pa r ameter i n evaluat i ng the em i ssion e ffi c i e n cy of a white LED. A molecu l e's efficiency t o f l u o r esce is described by its quantum yield and the inte r nal quantum ef f ic i ency i s def in ed as the r at i o of the number of photons emitted by t h e sample to t he n um b er of photons absorbed by the sample. FP-8500 3D Fl uo r escence Hi gh -Speed Measuremen t System Thi s appl i cat i on note i llustrates the measurement reproduc i bility of the internal quantum ef f iciency of t wo phosphor powders from the evaluat i on of a white LED. Keywords F P -8500，ESC-842 Ca li bra t ed Wi li g ht so urce， IS F -834 In te g r a tin g s ph ere ， P h o sp h ors， M a t er i als， F l u orescence， Q u a n tu m yie ld ， FWQE-880 Q ua nt um Y i eld Ca l c u l ati o n pr o gram Experimen t al Excitation Wavelength 455nm Scanning Speed 500 nm/min Emission Bandwidth 5nm Excitation Bandwidth 5nm Response 0.1 sec Sensitivity 355V T o cal c u l a t e th e in terna l qua nt um ef f icien cy ， b o th th e sample spec tr um and inc i de n t l i g h t s p ectru m must be measu r ed .The i n ciden t l i g h t spec tr um i s th e em i ssion spectr u m of t he exci t ation l ig h t scattered by a BaSO r ef l ectance sta n dard，s h own in Fi g u r e 1. A ca li bra te d l i gh t sou r c e i s th en u s e d f or s p e ctra l c or re c t i o n of th e me asure d sp ec t ru m . Figure 1. Meas u rem e n t of the i ncident light (lef t ) a n d samp l e f l uo r escence a n d exc i t a tion scat t e r ed l igh t us i ng t he integr a t in g sp h ere. Re sults T o co n fir m reprod u ci b i lit y ， fi v e repea t m easu r e m e n t s w e r e m a d e f o r eac h sample (b y r efi lling the sample ce l l ) a n d a r e s hown in F i g u r e 2 and 3. Hig h reproduc ib i lit y was o b t ained fo r bo th pho s ph o r measu r e m en t s as in d i cate d b y the d iff er e nce bet we e n the m a ximum a n d minimu m v a lue s of th e i n ter n al q u a n tu m ef fi c i ency (w ith in 1.5% w ith a c o e f f ici e nt o f v a ri a nce o f 0.6%)， shown in Ta bl e 1 an d 2. Figure 2. Inc i dent lig h t spectr um (b l ack)， fl u orescence spectr u m Figure 3. Incide nt ligh t s p e ctru m (b lack)， f l uo r esce n ce s p ectrum of r ed phos p h o r sam p le 1 (red )， sample 2 (blue)，sam p le 3 (gree n )， sam p le 4(pin k )， and sample 5 (l ight bl u e).Inset ： zoomed in fluoresce n ce spect r um aro u nd 550 n m peak. 28600 Mary's Cour t ， E a s to n ， M D 21601US A Table 1. Calcu l ated res u lts of t h e inter n al q u antum efficiency of the yellow phosphor . Number of Measurement Sample Absorption Rate (%) External Quantum Efficiency (%) Internal Quantum Efficiency (%) 1 87.6 80.7 921 2 87.4 80.3 91.9 3 87.3 79.9 91.6 4 87.2 79.7 91.4 5 87.1 79.0 90.7 Average 87.3 79.9 91.5 SD 0.19 0.64 0.54 C.V. 0.22 0.80 0.59 Table 2. Calc u lated res u lts of t h e i n ter n al q ua ntum ef fi c i e nc y of t he yellow ph o sp ho r . Number of Measurement Sample Absorption Rate (%) External Quantum Efficiency (%) Internal Quantum Efficiency (%) 1 78.2 65.8 84.1 2 77.6 64.9 83.6 3 77.9 65.9 84.6 4 77.8 65.4 84.1 5 77.9 66.1 84.9 Average 77.9 65.6 84.3 SD 0.22 0.48 0.50 C.V. 0.28 0.73 0.60 28600 Mary's Cour t ， E a s to n ， M D 21601US A