Halide perovskites sun kawo sauyi a fannin photovoltaics tare da kyawawan halayensu na optoelectronic, waɗanda aka fi inganta su ta hanyar injiniyanci na interfacial a cikin ƙwayoyin hasken rana. Duk da haka, yayin da aikin ya kusanci iyakokin ka'idar na al'ada na p-n junction physics, akwai buƙatar gaggawa don bincika wasu hanyoyin photovoltaic na madadin. Wannan binciken ya bincika tasirin flexo-photovoltaic (FPV)—wani tasirin photovoltaic na gabaɗaya (BPVE) wanda gradients na matsi ke motsa shi—a cikin methylammonium lead halide perovskites (MAPbBr3 da MAPbI3). Binciken ya nuna cewa waɗannan kayan suna nuna tasirin FPV wanda ya fi girman ma'aunin oxide SrTiO3 da yawa, kuma, mahimmanci, na iya samar da photovoltages da suka wuce nasu bandgap a ƙarƙashin isassun gradients na matsi. Wannan aikin ya nuna cewa injininiyar gradient na matsi na iya samar da sabon tsari na aiki don haɓaka aikin na'urorin halide perovskite fiye da iyakokin al'ada.
Fahimtar tasirin flexo-photovoltaic yana buƙatar tushe a cikin ƙa'idodin daidaito na asali da hanyoyin photovoltaic da suka wanzu.
Kwararar gabaɗaya ta abubuwan da ke ɗauke da caji da aka haifa ta haske (photocurrent) yana buƙatar karya daidaiton juyawa na sarari. A cikin ƙwayoyin hasken rana na al'ada, wannan karya daidaito yana faruwa a mahaɗar p-n junction, yana raba nau'ikan electron-hole.
A cikin wasu lu'ulu'u marasa tsakiya (misali, piezoelectric), ana karya daidaiton juyawa na sarari a cikin kayan gabaɗaya. Hasken zai iya haifar da photocurrent mai tsayayye, wanda aka sani da tasirin photovoltaic na gabaɗaya, ba tare da buƙatar mahaɗa ba. Canjin halin yanzu, babbar hanyar, ana iya kwatanta shi ta hanyar bayyanawa.
Flexoelectricity wani dukiya ne na duniya inda gradient na matsi ($\nabla \epsilon$) ya haifar da polarization ($P$) a cikin kowane abu na dielectric: $P_i = \mu_{ijkl} \frac{\partial \epsilon_{jk}}{\partial x_l}$, inda $\mu$ shine tensor na flexoelectric. Lanƙwasa crystal yana haifar da irin wannan gradient, yana karya daidaito kuma yana ba da damar BPVE da gradient na matsi ke motsa shi, watau tasirin flexo-photovoltaic. Wannan tasirin yana yiwuwa a ka'ida a cikin kowane abu a ƙarƙashin lanƙwasa.
An haɗa lu'ulu'u guda ɗaya na MAPbBr3 (MAPB) da MAPbI3. Lu'ulu'u guda ɗaya na kasuwanci na SrTiO3 (STO) sun yi aiki azaman ma'auni na flexoelectric. An ƙirƙira sifofin capacitor masu daidaito ta hanyar ajiye na'urorin lantarki na Au iri ɗaya a fuskoki masu kishiya na lu'ulu'u.
An lanƙwasa lu'ulu'u ta hanyar injina don amfani da gradient na matsi da aka sarrafa. Hasken gefe (LED 405 nm don MAPB, 365 nm don STO) ya tabbatar cewa gudummawar photovoltaic da ke da alaƙa da mahaɗa daga na'urorin lantarki guda biyu masu daidaito sun soke juna, suna ware tasirin gabaɗaya. An auna photovoltage a matsayin aikin lanƙwasa curvature (gradient na matsi) da ƙarfin haske (har zuwa 1000 LUX).
Halide Perovskites >> SrTiO3
> Bandgap An Samu
FPV + BPVE na Asali
An gano tasirin flexo-photovoltaic da aka auna a cikin MAPbBr3 da MAPbI3 ya fi girma da yawa fiye da na oxide mai tunani SrTiO3. Wannan ya nuna ƙaƙƙarfan haɗin kai tsakanin gradients na matsi da rabuwar caji a cikin halide perovskites, wanda aka danganta shi da manyan ƙididdiga na dielectric da motsi na ionic, waɗanda ke haɓaka ƙididdiga na flexoelectric.
Wani binciken da ya shahara shi ne cewa don isassun manyan gradients na matsi da aka yi amfani da su, photovoltage da aka samar zai iya wuce ƙarfin lantarki na bandgap na kayan ($V_{ph} > E_g / e$). Wannan ya saba wa iyakar Shockley-Queisser ta al'ada don ƙwayoyin hasken rana guda ɗaya, wanda ya dogara da ilimin lissafi na mahaɗa, kuma yana nuna bambanci na asali kuma mai yuwuwar mafi girman rufin canjin makamashi na tushen tasirin gabaɗaya.
A cikin MAPbI3, an sanya photovoltage na flexo akan wani photovoltage na asali na gabaɗaya na asali, mai hysteretic. Wannan hysteresis ya yi daidai da polarization na macroscopic na lantarki mai canzawa na kayan, yana nuna haɗin kai tsakanin yankuna na ferroelectric (ko kama da ferroelectric) da amsawar photovoltaic. Tasirin suna ƙarawa, suna nuna yuwuwar haɓaka hanyoyi da yawa.
Ana iya haɗa yawan ƙarfin lantarki na flexo-photovoltaic $J_{FPV}$ da kaddarorin kayan da sigogi na gwaji ta hanyar bayyanawa:
$J_{FPV} \propto \beta \cdot I \cdot \nabla \epsilon$
Inda $\beta$ shine ƙayyadaddun ƙimar FPV na musamman na kayan wanda ya haɗa da tensor na flexoelectric da kaddarorin jigilar abubuwan ɗauke da caji, $I$ shine ƙarfin haske, kuma $\nabla \epsilon$ shine gradient na matsi. Photovoltage na buɗe kewaye $V_{oc}$ yana da alaƙa da wannan halin yanzu da juriyar ciki na samfurin. Yanayin don photovoltage sama da bandgap yana nuna cewa samfurin $\beta \cdot \nabla \epsilon$ a cikin waɗannan perovskites na iya zama babba sosai don tuƙi masu ɗauke da caji a kan bambancin yuwuwar da ya fi $E_g/e$. Amsar hysteretic a cikin MAPbI3 tana nuna polarization mai dogaro da lokaci $P(t)$ wanda ke gyara filin ciki: $J_{total} \propto (\beta_{FPV} \cdot \nabla \epsilon + \gamma \cdot P(t)) \cdot I$, inda $\gamma$ shine ƙimar haɗin kai.
Tsarin don Kimanta Sabbin Hanyoyin PV:
Aikace-aikacen Nazarin Lamari: Yin amfani da wannan tsarin ga takardar da aka gabatar ya nuna a sarari aiwatar da shi: sifofi masu daidaito sun ware tasirin gabaɗaya, lanƙwasa ya sarrafa $\nabla \epsilon$, STO ya ba da ma'auni, kuma gano >$E_g$ $V_{oc}$ ya kasance sakamakon gwajin iyaka. Halin hysteretic ya jawo bincike kan yanayin polarization na asali.
Wannan ba kawai ƙarin haɓaka inganci ba ne; yana da kai hari kan tsarin iyakar Shockley-Queisser. Marubutan sun yi amfani da nakasu na injiniyan kayan—wani abu da aka saba ɗauka a matsayin mafarki na dogaro—don samar da photovoltages waɗanda a ka'ida ba za su yiwu ba a cikin kayan lokaci guda. Sun motsa yaƙin don ƙarin inganci daga injiniyanci na nano na mahaɗa zuwa injiniyanci na macro da micro na filayen matsi. Abubuwan da ke tattare da su suna da zurfi: idan rufin don Si guda ɗaya shine ~29%, kuma don perovskites shine ~31%, hanyar da ba ta daure da cikakken ma'auni tana buɗe sabon rufin, wanda ba a bayyana shi ba.
Hankali yana da kaifi kuma mai raguwa. 1) Ana buƙatar sabon ilimin lissafi na PV bayan mahaɗa. 2) Tasirin gabaɗaya kamar BPVE madadin ne. 3) Flexoelectricity na iya haifar da BPVE (FPV) a cikin kowane abu mai lanƙwasa. 4) Halide perovskites sune manyan kayan PV kuma an san suna da flexoelectric sosai. 5) Don haka, gwada FPV nasu. 6) Sakamako: Yana da girma sosai kuma yana iya karya shingen ƙarfin lantarki na bandgap. Silsilar tunani ba ta da iska, tana canza sha'awar ka'ida (FPV a cikin oxides) zuwa fasaha mai yuwuwar rushewa a cikin dangin kayan PV mafi zafi.
Ƙarfi: Ƙirar gwaji yana da kyau a cikin sauƙinsa don ware tasirin. Sakamakon >$E_g$ shine kanun labarai, tabbataccen tabbatar da yuwuwar ra'ayin. Yin amfani da STO azaman ma'auni yana ba da mahimmancin mahallin. Lura da ƙarawa tare da polarization na asali a cikin MAPbI3 yana nuna wurin wasa mai wadata don ingantaccen ilimin lissafi da yawa.
Kurakurai & Gaps: Wannan binciken kimiyya ne na asali, na lu'ulu'u guda ɗaya. Giwa a cikin daki shine aiwatarwa mai amfani. Ta yaya za ka gabatar da manyan, sarrafa, kuma barga gradients na matsi a cikin ƙwayar hasken rana mai bakin ciki a kan tushe mai sassauƙa ba tare da haifar da gajiya ko karyewa ba? Takardar ba ta da maganar ma'aunin canjin ƙarfi (PCE)—samar da babban ƙarfin lantarki wani abu ne, amma cire amfani da ƙarfi (halin yanzu x ƙarfin lantarki) wani abu ne. Kwanciyar hankali na tasirin a ƙarƙashin ci gaba da haske da keke na injini ba a magance shi gaba ɗaya ba, wani mahimmin tsallakewa ga kowane aikace-aikacen duniya na gaske.
Ga masu bincike: Mataki na gaba nan da nan shine nuna wannan a cikin fina-finai masu bakin ciki. Yi haɗin gwiwa tare da ƙungiyoyin ƙwararrun injiniyan matsi (misali, ta amfani da tushe marasa daidaituwa, nanoparticles na core-shell, ko yadudduka masu matsi). Auna cikakken lanƙwasa J-V kuma a ba da rahoton PCE da FPV ya ba da gudummawa. Bincika wasu perovskites na haɗin gwiwa da bambance-bambancen 2D waɗanda ƙila suna da mafi girman ƙididdiga na flexoelectric.
Ga masu saka hannun jari: Wannan babban haɗari ne, babban lada, farkon matakin fare. Kar a yi tsammanin na'urorin kasuwanci a cikin shekaru 5 masu zuwa. Duk da haka, ku ba da kuɗi ga ƙungiyoyin da ke tunkarar kalubalen haɗin kayan da injiniyan injiniya. IP game da hanyoyin saka ƙirar gradients na matsi a cikin na'urorin PV na iya zama mai matuƙar ƙima idan da'awar inganci ta tsaya a sikeli.
Ga masana'antu: Dubi wannan a matsayin zaɓi na dorewa na dogon lokaci Ci gaba da inganta ƙwayoyin hasken rana na perovskite na interfacial (PSCs) don turawa na kusa, amma a ware ƙaramin ƙungiyar R&D mai sauri don bin diddigin gwaje-gwaje tare da ra'ayoyin tasirin gabaɗaya. Lada mai yuwuwa—ƙwayar hasken rana tare da mafi girman iyakar inganci na asali—ya ba da hujjar tsarin fayil.