Solar Cell Applications of Solution-Processed AgInGaSe2 Thin Films and Improved Properties by Sodium Doping.

Xianfeng Zhang,Qingxuan Sun,Maoxi Zheng,Zhuohua Duan,Yuehui Wang

doi:10.3390/nano10030547

Xianfeng Zhang, Qingxuan Sun + Show 3 more

Open Access

https://doi.org/10.3390/nano10030547

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Abstract

Binary nanoparticle inks comprising Ag2Se, In2Se3, and Ga2Se3 were fabricated via a wet ball-milling method and were further used to fabricate AgInGaSe2 (AIGS) precursors by sequentially spraying the inks onto a Mo-coated substrate. AIGS precursors were annealed under a Se atmosphere for 1 h at 570 °C. Na2Se thin layers of varying thicknesses (0, 5, 10, and 20 nm) were vacuum-evaporated onto the Mo layer prior to the AIGS precursors being fabricated to investigate the influence on AIGS solar cells. Sodium plays a critical role in improving the material properties and performance of AIGS thin-film solar cells. The grain size of the AIGS films was significantly improved by sodium doping. Secondary ion mass spectroscopy illustrated slight surficial sodium segregation and heavy sodium segregation at the AIGS/Mo interface. Double-graded band profiles were observed in the AIGS films. With the increase in Na2Se thickness, the basic photovoltaic characteristics of the AIGS solar cells were significantly improved. The highest solar cell conversion efficiency of 6.6% (open-circuit voltage: 775.6 mV, short-circuit current: 15.5 mA/cm2, fill factor: 54.9%, area: 0.2 cm2) was obtained when the Na2Se thickness was 20 nm.

Highlights

The CuInGaSe2 (CIGS) thin-film solar cell is a very promising candidate for future large-area photovoltaic applications
Further research of tandem solar cells based on CIGS solar cells is necessary to further increase solar cell efficiency
A wide bandgap of >1.70 eV has been calculated for the top cell as necessary to achieve a high efficiency of >30% when CIGS solar cells are used as the bottom layer [3]

Summary

Introduction

The CuInGaSe2 (CIGS) thin-film solar cell is a very promising candidate for future large-area photovoltaic applications. The conversion efficiency of non-vacuum fabricated CIGS and CZTS solar cells has respectively reached 17.1% [11]. It can be observed that the peak intensity of AIGS films gradually increase with the increase in Na2Se thickness, indicating a better crystallinity. FFiigguurree 1122 sshhoowwss tthhee XX--rraayy pphhoottooeelleeccttrroonn ssppeeccttrroossccooppyy ssppeeccttrraa ooff ssooddiiuumm aanndd ooxxyyggeenn oonn tthhee ssuurrffaacceeoofftthheeAAIIGGSSfifillmmssaassaa ffuunnccttiioonnooffNNaa222Se post--ddeeppoossiittiioonntthhiicckknneessss. AAss tthhee thhiicckknneessss ooff ssooddiiuumm iinnccrreeaasseedd,, aann oobbvviioouuss NNaa ((11ss)) ppeeaakk wwaass oobbsseerrvveedd,, FFiigguurree 1121aa,, wwhhiicchh iiss ccoonnssiisstteenntt wwiitthh tthhee pprreevviioouuss SSIIMMSS oobbsseerrvvaattiioonnss ooff ssuurrffaaccee ssooddiiuumm sseeggrreeggaattiioonn. JJ––VV aanndd EEQQEE ccuurrvveess ooff tthhee cchhaammppiioonn eefffifffiicciieennccyy ffoorr tthhee AAIIGGSS ssoollaarr cceellllss aassaafffuuunnncccttiioonnooofffNNNaaa222SSee tthhiicckknneessss aarree sshhoowwnn iinn FFiigguurree111444aaa–––ccc. BBaasseedd oonn EEqquuaattiioonn 11,, FFiigguurree 1133cc,, aanndd tthhee ssoollaarriirirrrraaadddiiaiaattitoiioonnnspsspepceetccrtutrrmuumm, J,,scJJsosccfoothffetthhAeeIGAASIIGGsoSSlassrooclleaalrrl wcceealllsl cwwaalacssuclcaaatlleccduulalaastte8ed.d6 amassA88/.c.66mmm AfAo/r/cc0mmn22mffo,or1r000.6nnmmmA,,/1c1m00..626 mfmoArA5//ccnmmm22,ff1oo2rr.855mnnmAm/,,cm11222..88fommr A1A0//ccnmmm22,ffaoonrrd111004n.n2mmm,,Aaan/ncddm12144f..o22rmm20AAn//cmcmm. 22Tfhfooerrd22e00vninammtio.. nTThohefeJdsdceewvviiaaasttiicooannlcouofflaJJtsseccdwwbaayss ctchaalelccuQullEaattceeuddrbvbyey dtthheeeriQvQeEEdccfuurrorvvmee dtdheeerriiJvvseceddobffrtraooimmnettdhheebyJJssccthoobebttJaa–iiVnneecddubrbvyyett,hhaeenJdJ––VVisccrueurlravvtee,,daantnoddaiisslorrweellaeatrteeiddlluttoomaainllaootwwioeenrr iilnlllutuemmnsiinintayattioioofnnthiinnettQeennEssimittyyeoaofsfutthhreemQQeEEnmtmweeahasseuunrreceommmeenpntat wrwehdheetnno ctcohomamtppoaafrraeedsduttnoo-tithrhraaattdooifafataesdsuuennq--iuirrirrvaaaddlieiaanttete.ddeeqquuiivvaalleenntt

Conclusions

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