Cèl·lules solars de pel·lícula fina de selenur d'antimoni quasi unidimensional per a la fotovoltaica de nova generació

Pere Vidal Font

Saucedo Silva, Edgardo Izquierdo Roca, Víctor

This doctoral thesis explores the quasi-one-dimensional absorber material Sb2Se3 and its application in thin-film solar cells in a SLG/Mo/Sb2Se3/CdS/i-ZnO/ITO substrate configuration. First, characterization mechanisms based on Raman spectroscopy and X-ray diffraction techniques are developed to evaluate the basic physicochemical properties of the Sb2Se3 material and generate fundamental knowledge to adequately identify the phase and possible secondary phases obtained during the synthesis process of the thin films. 27 of the 30 theoretically predicted Raman peaks are identified by multi-wavelength and low-temperature Raman spectroscopy measurements, correlating with the observed XRD pattern and its difference between the as-grown and single-crystalline films. Based on the developed methodology, mechanisms for controlling the quality of the layers by non-invasive methods are proposed that allow for rapid and non-invasive analysis. In a second step, the synthesis route of Sb2Se3 is explored through a two-step sequential process based on the reactive annealing in a low selenium atmosphere of a previously physically evaporated antimony metal layer. The study focuses on the effects of temperature, time and pressure of the reactive annealing process and how these affect the final composition ratio of the Sb2Se3 system, reflected in an optimal range of values ​​of the ratio 3[Sb]/2[Se] = 0.8 - 0.9 and thus obtaining a maximum device efficiency of 5.7%. This development of the devices has been carried out through highly industrializable processes based on a sequential low-temperature route and substrate structure, which allows the adaptation to different substrates, both rigid like glass, flexible like thin steel sheets or flexible and transparent like polymers. These devices are studied and analyzed in more depth to reveal the limiting factors present that are mainly found in the device interfaces. Finally, a deeper investigation of the devices already optimized in terms of stability under temperatures between T = 50 - 350 °C is carried out. This study highlights a high instability in Sb2Se3 at temperatures as low as 50 °C, mainly reflected in the reduction of the volume of the unit cell of the Sb2Se3 system and its correlation with the decrease of the optoelectronic parameters obtained. Instability studies of emerging materials are fundamental for their rapid industrialization as they avoid future problems of adaptation to industrial processes and guide future research in a logical and coherent sense. The development of this Thesis has resulted in the collaboration of the A Prop-IREC center with other research centers, universities and companies in 4 European and National projects that are based on or use/expand the results presented here: SENSATE European Research Council (ERC) (Grant Agreement No 866018); MATER-ONE MICINN-AEI (requests 2020) (PID2020-116719RB-C42); HIDDEN-PV Submitted to the M-era.net 2022 call, which has passed the preselection step; FOTO-CER (MIG-20211047, Missions CDTI 2021).

Els resultats obtinguts en aquesta tesi van fer que la tecnologia fos molt atractiva per a la seva industrialització a causa d'aquests aspectes clau: i) es basa en materials inorgànics i està lliure de matèries primeres crítiques, cosa que és crucial per garantir una alta estabilitat i sostenibilitat a llarg termini; ii) contràriament a l'estàndard del desenvolupament tecnològic de Sb2Se3, té una configuració de substrat, es produeix en un procés seqüencial mitjançant tècniques de deposició física escalables i a baixes temperatures de síntesi i es pot fabricar sobre substrats polimèrics i metàl·lics flexibles; i iii) es pot ajustar mitjançant l'adaptació de la tecnologia Sb2Se3 a Sb2S3. La rellevància de la recerca en el camp es reflecteix en les 73 cites acumulades en revistes amb un factor d'impacte elevat. Aquests resultats van proporcionar al grup de recerca SEMS de l'IREC una nova experiència que va permetre la participació en diverses conferències internacionals i projectes nacionals i europeus, generant xarxes amb centres de recerca i indústries rellevants per a l'aplicació dels resultats a entorns rellevants. En aquest sentit, les característiques de les tecnologies desenvolupades les fan compatibles amb aplicacions fotovoltaiques integrades avançades en nínxols de mercat creixents com ara la fotovoltaica d'interior, l'alimentació de dispositius de la Internet de les coses (IoT), la fotovoltaica integrada en edificis (BIPV), la fotovoltaica integrada en vehicles (VIPV), l'agrovoltaica (APV)...

Quasi-one-dimensional absorber material; Sb2Se3; Thin-film solar cells; SLG/Mo/Sb2Se3/CdS/i-ZnO/ITO; Raman spectroscopy; X-ray diffraction; Physicochemical properties; Phase identification; Secondary phases; Thin-film synthesis; Multi-wavelength Raman; Low-temperature Raman; XRD pattern; As-grown films; Single-crystalline films; Non-invasive quality control; Rapid analysis; Two-step sequential process; Reactive annealing; Physically evaporated antimony; Low selenium atmosphere; Temperature effects; Time effects; Pressure effects; Composition ratio; 3[Sb]/2[Se] ratio; Device efficiency; Highly industrializable processes; Low-temperature route; Substrate structure; Rigid substrates; Flexible substrates; Transparent substrates; Glass; Thin steel sheets; Polymers; Limiting factors; Device interfaces; Stability under temperature; Unit cell volume reduction; Optoelectronic parameters; Instability studies; Industrialization; Future research; A Prop-IREC; Research collaborations; European projects; National projects; SENSATE European Research Council (ERC); MATER-ONE MICINN-AEI; HIDDEN-PV; FOTO-CER.