NOVELTY - Passivating a silicon substrate (100) involves: providing a silicon substrate having a bulk and exhibiting front and rear surfaces; and forming by liquid phase application a dielectric layer (103) on at least the rear surface; where the dielectric layer formed at the rear surface is capable of acting as a reflector to enhance reflection of light into the bulk of the substrate, and is capable of releasing hydrogen into the bulk as well as onto a surface of the substrate in order to provide hydrogenation and passivation.    USE - For passivating a silicon substrate for use in a photovoltaic device such as solar cell (all claimed).    ADVANTAGE - The present method modifies silicon solar substrates by liquid phase deposition while avoids the use of hazardous chemicals and conditions. The present method provides an inexpensive, low cost method of improving the electrical and/or optical performance of photovoltaic devices through the application of coating chemicals onto the backside of the silicon substrate. An increase of the efficiency of the current extraction and a reduction of recombination occur within the device. This results in greater power output from the device. The present procedure offers an alternative to the existing Atomic Layer Deposition (ALD) or Plasma Enhanced Chemical Vapor Deposition (PECVD) method using trimethylaluminum (TMA), silane (SiH4) and other gases, enabling the photovoltaic (PV) manufacturers to apply chemicals rather than work with hazardous gases to produce a series of layers that provide passivation as well as light internal reflectance. This provides, in the case of thick film solar cell production, to have the whole manufacturing sequence performed using chemicals applied under atmospheric conditions and without the use of any hazardous gas or PECVD with the additional benefit of cost reduction and better process control and equipment sustainability.    DETAILED DESCRIPTION - Passivating a silicon substrate (100), involves: providing silicon substrate having a bulk and exhibiting front and rear surfaces; and forming by liquid phase application a dielectric layer (103) on at least the rear surface; where the dielectric layer formed at the rear surface is capable of acting as a reflector to enhance reflection of light into the bulk of the substrate, and is capable of releasing hydrogen into the bulk as well as onto a surface of the substrate in order to provide hydrogenation and passivation. The method involves forming a dielectric, hydrogen releasing and optionally anti-reflecting layer on the front surface. The dielectric layer has a thickness of 5 to 250 nm. The layer formed on the front is capable of reducing surface and bulk recombination, and improves light absorption, when the silicon substrate is used in a photovoltaic device. The method involves additionally forming at the rear surface a layer of aluminum oxide (Al2O3) having a thickness of 1-50 nm, preferably 3-30 nm, by plasma-enhanced chemical vapor deposition, by sputtering, or by atomic layer deposition. The method involves passivating or reflecting layer comprising silicon carbide, and/or silicon oxide material, for passivating n type silicon surface, or an aluminum oxide or aluminum oxide and silicon oxide hybrid, optionally with a titanium oxide cap, for passivating p type silicon surface. The passivating layer comprises silicon, oxygen and hydrogen; or silicon, carbon and hydrogen; or silicon, carbon, oxygen and hydrogen for the emitter of p-type solar cell and for the back side of n-type solar cell. The passivating layer comprises aluminum, oxygen, and hydrogen for the back side of p-type solar cell or for the front side of n-type solar cell; the passivating layer comprises titanium, oxygen, and hydrogen for the back side of p-type solar cell or for the front side of n-type solar cell; the passivating layer comprises aluminum, titanium, oxygen, and hydrogen for the back side of p-type solar cell or for the front side of n-type solar cell. The passivating layer is formed by polymerizing Si(OR1)4 and/or HSi(OR1)3 (where R1 is an alkyl group, preferably a linear or branched alkyl group having 1 to 8 carbon atoms, in particular a linear or branched alkyl group having 1 to 4 carbon atoms); by polymerizing Al(iOPr)3 and Ti(iOPr)4 and HSi(OR1)3 (for aluminum oxide); by polymerizing Ti(iOPr)4, HSi(OR1)3 and TiCl4 (for titanium oxide); by polymerizing HSi(OR1)3 and Al(iOPr)3 (for aluminum oxide and silicon oxide hybrid); or by polymerizing at least one monomer of formula SiX3CH2X, where X is a halogen group.    DESCRIPTION OF DRAWING(S) - The figure shows a cross sectional view of the process flow for manufacturing a p-type crystalline silicon solar cell incorporating dielectric(s) in it.    Boron doped p-type silicon substrate (100)    Negative phosphorus doped region (101)    Anti-reflection coating (102)    Dielectric (103)    Contact opening (104)