IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 9, September 2015.

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1 P P P P solar IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN etermato Of The Jucto Surface recombato Velocty mtg The Ope Crcut (Sfoc) For A Bfacal Slco Solar Cell Uder Exteral Electrc Feld. PMarcel Stor IOUF, P PGoha SAHIN, P PAmary THIAM, P PKhady FAYE P PMoussa Ibra NGOM, P Poudou GAYE, P PGrégore SISSOKO PUversty of Chekh Ata op, akar/seegal, Faculty of Sceces ad Techques, Physcs epartmet. PUversty of Chekh Ata op, akar/seegal,3t Polytechc3T 3THgh School * Correspodg author: Grégore SISSOKO (34T Ugsssoko@yahoo.comU34T ). UAbstract I ths paper, we study the fluece of the electrc feld o the jucto recombato velocty lmtg the ope crcut. The excess of morty carrer s desty the base s determed from the cotuty equato. The photovoltage ad the ope crcut voltage are derved from the excess morty carrer s desty. From the photovoltage study, the jucto recombato velocty lmtg the ope crcut ad the ope crcut voltage are determed ad studed for dfferet values of electrc feld ad smultaeous llumato mode. Keywords : Solar Cell Electrc feld Jucto recombato velocty Ope crcut voltage I. Itroducto Photovoltac coverso s a drect trasformato of lght eergy to electrcal eergy through a devce called solar cell. Because of ther modest performace, may studes have bee developed order to mprove ther effcecy by dfferet processes [] ad through dfferet characterzato techques. The solar cell ca be placed uder statc codto [] ad dyamc mode (traset ad frequecy) [3], the the electrcal ad recombato parameters [4-8] are deduced. As part ths work, our cotrbuto s to study the effect of polarzato electrc feld o the jucto surface recombato velocty lmtg the ope crcut through the ope crcut voltage. The study wll be doe o the solar cell remaed uder smultaeous polychromatc llumato of the two sdes. I ths study, we cosder a P P-ppP + + II. Theory cell type [9], double sde surface llumated ad uder exteral polarzato by applyg a voltage. The effect of exteral electrc feld resultg from the polarzato behavor of the charge carrers the base s studed by help wth the assumpto of the quas-eutral base (QNB) [0]. theory s. Fgure shows the structure of the solar cell depedg o the model uder study. 93

2 P type IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN Fgure : Bfacal solar cell structure to the P PppP uder electrc polarzato ad polychromatc llumato. II.. étermato of the morty carrer s desty The cotuty equato for the excess morty carrer s desty photo-geered the base uder fluece of the electrc feld s: δ ( x) µ. E δ ( x) G + + x x ( x) δ ( x) 0 () δ(x) s the excess morty carrers desty accordg to the depth x the base of the solar cell, followg the smultaeous double sde surface llumato mode. E represets the electrc feld, the dffuso coeffcet, the dffuso legth, µ the carrer moblty. Posg : µ. E. E () Equato () becomes: δ ( x) + x E δ ( x) G + x ( x) δ ( x) 0 (3) 93

3 brr ad 30 stem IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN The expresso of G (x) depeds o the x depth of lght absorpto the base ad ca be wrtte the form of the followg equato []. G( x) 3 a b b ( H x) ( e + e ) (4) The parameters arr brr from the modelg of the cdet llumato as defed by uder A.M.5 codto []. H s the thckess of the base. 0-3 Where, arr 6.3x0P P cmp cmp P; br3r cmp P; P/s; arr x0P P cmp P/s; ar3r 0.099x0P 0 P cmp -3 P/s; brr cmp P ; The soluto δ(x) of the carrers dffuso equato () s obtaed the followg forms: δ ( x) e βx ( ) b. x b.( H x) [ A ch( φ x) + B sh( φ x) ] + c e + e 3 (5) Wth the dfferet coeffcets expressed as: φ ( E + 4 ), β E c [ a E b b ] The coeffcets A ad B are solved wth the boudary codtos at the emtter base jucto ad at the back surface of the cell [, 3]: -at the jucto (x0): Sf δ δ ( x) ( 0) x x 0 (6) -at the back surface (xh) : δ ( x) Sb δ ( H ) x x H (7) Sf ad Sb are respectvely the jucto ad back surface recombato velocty [0, ]. We plot fgure, the morty carrer s desty versus base depth for dfferet values of electrc polarzato feld 933

4 VRTR s the IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN Fgure : Morty carrer s desty versus base depth for dfferet values of electrc polarzato feld (Sf4.0P Pcm/s, µ0p PcmP PVP PsP P, 0.0cm, H0.03cm, 6cmP P.sP P) II.. Photovoltage The expresso of the photovoltage s obtaed from the followg relato V ph the thermal voltage, R Rthe trsc carrer desty at thermal equlbrum ad NRBR base dopg desty. N b V l δ (0) T + (8) We plot fgure 3, the photovoltage versus jucto recombato velocty. 934

5 IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN Fgure 3 : Photovoltage versus jucto recombato velocty for dfferet values of electrc feld (µ0p PcmP PVP PsP P, 0.0cm, H0.03cm, 6cmP P.sP P) II.. etermato of the jucto recombato velocty lmtg the ope crcut voltage For low values of the jucto recombato velocty, the photovoltage s maxmum ad costat. The excess morty carrers are the stored at the jucto. Takg to accout prevous work [4] ad keepg our terest ths flat part of the photovoltage curves, we ca deduce the codto yeldg the jucto surface recombato lmtg the ope crcut voltage by the followg equato. Vph(Sf) - Voc 0 (9) Voc represets the ope crcut voltage ad s gve as: Voc lm Vph( Sf ) (0) Sf Sfoc Sfco E b. H (. β. E F )(.. b E. e + G) ( G. b. E)(.. β. E F ) b. H b. H E(. β. E F ) e + E( E.. b e + G) ( Sb +. β ). Sh( H ) +. Ch( H ) () (-) 935

6 PsP PsP P) IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. [( Sb +. β ). Ch( H ) +. Sh( H )]. φ F. H ( β + b ) ( +. b ) e G φ. Sb. Sb µ. E.. Ch( H ). Ch( φ [. α ( µ. E +. β ).. β ].. H ) ( µ. E + ). Sh( H ) Sh( H ) ISSN (-) (-3) (-4) We plot Fgure 4, the relatve values of jucto recombato velocty lmtg the ope crcut ad the ope crcut voltage versus the electrc feld Fgure 4: Relatve values jucto recombato velocty ad ope crcut voltage versus electrc feld (6cmP P/s, µ0p PcmP P.VP P, τ0p Fgure 4 shows the evoluto of the relatve values of the recombato velocty at the jucto as that of the ope crcut voltage accordg to the electrc feld as descrbed above. We obta the value of the electrc feld whe the relatve value of the ope crcut voltage tercepts wth the relatve value of jucto recombato velocty The values of the ope crcut voltage ad the recombato rate obtaed are hgher tha those obtaed for the llumato from the frot sde [5]. 936

7 IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. Cocluso ISSN I ths work, the excess of morty charge carrers desty the base s determed ad ts curve accordg the base depth for dfferet values of electrc feld ad for smultaeous llumato mode s preseted. The excess of the photovoltage s deducted from that of morty carrer s desty ad ther profle depedg the jucto recombato velocty for dfferet values the electrc feld ad for proposed llumato mode. Thus, the jucto recombato velocty lmtg the ope crcut voltage s determed for the solar cell uder electrc polarzato. REFERENCES [] M. Zougraa, M. Thame, A. oum, S. Ragulaba, G. Sssoko, «3 Study of a Bfacal Slco Solar Cell uder Itese ght Cocetrato ad uder Exteral Costat Magetc Feld: Recombato ad Electrcal Parameters etermato», Proceedgs of the d Europea Photovoltac Solar Eergy Coferece ad Exhbto-Italy (007).pp []. M. M. oe, A. ao, M. Ndaye, H. y allo, N. Tham, F. I. Barro, M.Wade, A. S. Maga, G. Sssoko, «3 study of a moofacal slco solar cell uder costat moocrhomatc lght: fluece ofgra sze, gra boudary recombato velocty, llumato wavelegth, back surface th ad jucto recombato veloctes» Proceedgs of 5P P Europea photovoltac solar eergy Coferece ad Exhbto (00), pp [3] S. Mbodj, A. S. Maga, M. eg, A. Wereme ad G. Sssoko «Reoval charge techc appled to a bfacal solar cell uder costat magetc feld», global joural of pure ad appled sceces vol 6, NO pp [4] H. El. Ghta ad S. Martzuz, «Ifluece of dslocatos o electrcal propertes of large graed polycrystalle slco cells» J. App. Phys. 66(4), 989, pp [5] Ala Rcaud, «Photoples Solares», Presses Polytechques et Uverstares Romades, 997 [6] J.W. Ortom ad P. Blood, The electrcal characterzato of semcoductors: Measuremet of morty carrer propertes", Academc Press. [7] H.Matheu, 937

8 IJISET - Iteratoal Joural of Iovatve Scece, Egeerg & Techology, Vol. Issue 9, September 05. ISSN «Physque des sem-coducteurs et des composats électroque» (Masso, pars, 987) [8] A. eg, A. ao, A.S. Maga, A. oum, I. y, G. Sssoko, «A Bfacal Slco Solar Cell Parameters etermato by Impedace Spectroscopy», Proceedgs of the d Europea Photovoltac Solar Eergy Coferece ad Exhbto-Italy (007), pp T[9] 39Te Quag Nam, M. Rodot, J. Njs, M. Ghaam0T 0Tad J. Coppye0T,.0T «Répose spectrale de photoples de haut redemet au slcum multcrstall.» TJ. Phys. III (Frace0T T 0T,0T 99), pp. 0T T [0].. Pulfrey, «Uderstadg Moder Trasstors ad odes.», Cambrdge Uversty Press, 00 [] Furla, J. ad S. Amo, «Approxmato of the carrer geerato rate llumated slco. Sold State Electro», 8 (985), pp [] S. N. Mohammad, «A alteratve method for the performace aalyss of slco solar cells.» J. Appl. Phys. 6() 987, pp [3] Sssoko, G., C. Museruka, A. Corréa, I. Gaye ad A.. Ndaye,. «ght spectral effect o recombato parameters of slco solar cell. Reewable Eergy.» 3(996), pp [4] I.y, M. Ndaye, M. Wade, Ndeye Tham, Sega Gueye, G. Sssoko Cocept Of Recombato Velocty S fcc At The Jucto Of A Bfacal Slco Solar Cell, I Steady State, Itatg The Short-Crcut Codto Research Joural Of Appled Sceces, Egeerg Ad Techology 5(): 03-08, 03 [5] Marcel Stor IOUF, Idrssa GAYE, Amary THIAM, Mame Faty Mbaye FA, Ibrahma Y, Grégore SISSOKO Jucto recombato velocty duced ope crcut voltage for a slco solar cell uder exteral electrc feld. Curret Treds Techology & Sceces (CTTS).Volume 3, Issue: 5, (Aug-Sept 04), pp